path: root/erts/emulator/beam/external.c

/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 1996-2016. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * %CopyrightEnd%
 */

/*  Implementation of the erlang external format 
 *
 *  And a nice cache mechanism which is used just to send a
 *  index indicating a specific atom to a remote node instead of the
 *  entire atom.
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#define ERTS_WANT_EXTERNAL_TAGS

#include "sys.h"
#include "erl_vm.h"
#include "global.h"
#include "erl_process.h"
#include "error.h"
#include "external.h"
#define ERL_WANT_HIPE_BIF_WRAPPER__
#include "bif.h"
#undef ERL_WANT_HIPE_BIF_WRAPPER__
#include "big.h"
#include "dist.h"
#include "erl_binary.h"
#include "erl_bits.h"
#include "erl_zlib.h"
#include "erl_map.h"

#define in_area(ptr,start,nbytes) ((UWord)((char*)(ptr) - (char*)(start)) < (nbytes))

#define MAX_STRING_LEN 0xffff

/* MAX value for the creation field in pid, port and reference
   for the local node and for the current external format.

   Larger creation values than this are allowed in external pid, port and refs
   encoded with NEW_PID_EXT, NEW_PORT_EXT and NEWER_REFERENCE_EXT.
   The point here is to prepare for future upgrade to 32-bit creation.
   OTP-19 (erts-8.0) can handle big creation values from other (newer) nodes,
   but do not use big creation values for the local node yet,
   as we still may have to communicate with older nodes.
*/
#define ERTS_MAX_LOCAL_CREATION (3)
#define is_valid_creation(Cre) ((unsigned)(Cre) <= ERTS_MAX_LOCAL_CREATION)

#undef ERTS_DEBUG_USE_DIST_SEP
#ifdef DEBUG
#  if 0
/*
 * Enabling ERTS_DEBUG_USE_DIST_SEP can be useful when debugging, but the
 * result refuses to talk to nodes without it!
 */
#    define ERTS_DEBUG_USE_DIST_SEP
#  endif
#  define IF_DEBUG(X) X
#else
#  define IF_DEBUG(X)
#endif

/* Does Sint fit in Sint32?
 */
#define IS_SSMALL32(x) (((Uint) (((x) >> (32-1)) + 1)) < 2)

/*
 *   Valid creations for nodes are 1, 2, or 3. 0 can also be sent
 *   as creation, though. When 0 is used as creation, the real creation
 *   is unknown. Creation 0 on data will be changed to current
 *   creation of the node which it belongs to when it enters
 *   that node.
 *       This typically happens when a remote pid is created with
 *   list_to_pid/1 and then sent to the remote node. This behavior 
 *   has the undesirable effect that a pid can be passed between nodes,
 *   and as a result of that not being equal to itself (the pid that
 *   comes back isn't equal to the original pid).
 *
 */

static Export term_to_binary_trap_export;

static byte* enc_term(ErtsAtomCacheMap *, Eterm, byte*, Uint32, struct erl_off_heap_header** off_heap);
struct TTBEncodeContext_;
static int enc_term_int(struct TTBEncodeContext_*,ErtsAtomCacheMap *acmp, Eterm obj, byte* ep, Uint32 dflags,
			struct erl_off_heap_header** off_heap, Sint *reds, byte **res);
static Uint is_external_string(Eterm obj, int* p_is_string);
static byte* enc_atom(ErtsAtomCacheMap *, Eterm, byte*, Uint32);
static byte* enc_pid(ErtsAtomCacheMap *, Eterm, byte*, Uint32);
struct B2TContext_t;
static byte* dec_term(ErtsDistExternal*, ErtsHeapFactory*, byte*, Eterm*, struct B2TContext_t*);
static byte* dec_atom(ErtsDistExternal *, byte*, Eterm*);
static byte* dec_pid(ErtsDistExternal *, ErtsHeapFactory*, byte*, Eterm*, byte tag);
static Sint decoded_size(byte *ep, byte* endp, int internal_tags, struct B2TContext_t*);
static BIF_RETTYPE term_to_binary_trap_1(BIF_ALIST_1);

static Eterm erts_term_to_binary_int(Process* p, Eterm Term, int level, Uint flags, 
				     Binary *context_b);

static Uint encode_size_struct2(ErtsAtomCacheMap *, Eterm, unsigned);
struct TTBSizeContext_;
static int encode_size_struct_int(struct TTBSizeContext_*, ErtsAtomCacheMap *acmp, Eterm obj,
				  unsigned dflags, Sint *reds, Uint *res);

static Export binary_to_term_trap_export;
static BIF_RETTYPE binary_to_term_trap_1(BIF_ALIST_1);
static BIF_RETTYPE binary_to_term_int(Process* p, Uint32 flags, Eterm bin, Binary* context_b,
				      Export *bif, Eterm arg0, Eterm arg1);

void erts_init_external(void) {
    erts_init_trap_export(&term_to_binary_trap_export,
			  am_erts_internal, am_term_to_binary_trap, 1,
			  &term_to_binary_trap_1);

    erts_init_trap_export(&binary_to_term_trap_export,
			  am_erts_internal, am_binary_to_term_trap, 1,
			  &binary_to_term_trap_1);
    return;
}

#define ERTS_MAX_INTERNAL_ATOM_CACHE_ENTRIES 255

#define ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTE_IX(IIX) \
  (((((Uint32) (IIX)) >> 1) & 0x7fffffff))
#define ERTS_DIST_HDR_ATOM_CACHE_FLAG_BIT_IX(IIX) \
  (((IIX) << 2) & 7)
#define ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTES(NO_ATOMS) \
  (((((Uint32) (NO_ATOMS)) >> 1) & 0x7fffffff)+1)

#define ERTS_DIST_HDR_LONG_ATOMS_FLG (1 << 0)

/* #define ERTS_ATOM_CACHE_HASH */
#define ERTS_USE_ATOM_CACHE_SIZE 2039
#if ERTS_ATOM_CACHE_SIZE < ERTS_USE_ATOM_CACHE_SIZE
#error "ERTS_USE_ATOM_CACHE_SIZE too large"
#endif

static ERTS_INLINE int
atom2cix(Eterm atom)
{
    Uint val;
    ASSERT(is_atom(atom));
    val = atom_val(atom);
#ifdef ERTS_ATOM_CACHE_HASH
    val = atom_tab(val)->slot.bucket.hvalue;
#endif
#if ERTS_USE_ATOM_CACHE_SIZE == 256
    return (int) (val & ((Uint) 0xff));
#else
    return (int) (val % ERTS_USE_ATOM_CACHE_SIZE);
#endif
}

int erts_debug_max_atom_out_cache_index(void)
{
    return ERTS_USE_ATOM_CACHE_SIZE-1;
}

int
erts_debug_atom_to_out_cache_index(Eterm atom)
{
    return atom2cix(atom);
}

void
erts_init_atom_cache_map(ErtsAtomCacheMap *acmp)
{
    if (acmp) {
	int ix;
	acmp->long_atoms = 0;
	for (ix = 0; ix < ERTS_ATOM_CACHE_SIZE; ix++)
	    acmp->cache[ix].iix = -1;
	acmp->sz = 0;
	acmp->hdr_sz = -1;
    }
}

void
erts_reset_atom_cache_map(ErtsAtomCacheMap *acmp)
{
    if (acmp) {
	int i;
	acmp->long_atoms = 0;
	for (i = 0; i < acmp->sz; i++) {
	    ASSERT(0 <= acmp->cix[i] && acmp->cix[i] < ERTS_ATOM_CACHE_SIZE);
	    acmp->cache[acmp->cix[i]].iix = -1;
	}
	acmp->sz = 0;
	acmp->hdr_sz = -1;
#ifdef DEBUG
	for (i = 0; i < ERTS_ATOM_CACHE_SIZE; i++) {
	    ASSERT(acmp->cache[i].iix < 0);
	}
#endif
    }
}

void
erts_destroy_atom_cache_map(ErtsAtomCacheMap *acmp)
{

}

static ERTS_INLINE void
insert_acache_map(ErtsAtomCacheMap *acmp, Eterm atom, Uint32 dflags)
{
    /*
     * If the receiver do not understand utf8 atoms
     * and this atom cannot be represented in latin1,
     * we are not allowed to cache it.
     *
     * In this case all atoms are assumed to have
     * latin1 encoding in the cache. By refusing it
     * in the cache we will instead encode it using
     * ATOM_UTF8_EXT/SMALL_ATOM_UTF8_EXT which the
     * receiver do not recognize and tear down the
     * connection.
     */
    if (acmp && acmp->sz < ERTS_MAX_INTERNAL_ATOM_CACHE_ENTRIES
	&& ((dflags & DFLAG_UTF8_ATOMS)
	    || atom_tab(atom_val(atom))->latin1_chars >= 0)) {
	int ix;
	ASSERT(acmp->hdr_sz < 0);
	ix = atom2cix(atom);
	if (acmp->cache[ix].iix < 0) {
	    acmp->cache[ix].iix = acmp->sz;
	    acmp->cix[acmp->sz++] = ix;
	    acmp->cache[ix].atom = atom;
	}
    }
}

static ERTS_INLINE int
get_iix_acache_map(ErtsAtomCacheMap *acmp, Eterm atom, Uint32 dflags)
{
    if (!acmp)
	return -1;
    else {
	int ix;
	ASSERT(is_atom(atom));
	ix = atom2cix(atom);
	if (acmp->cache[ix].iix < 0) {
	    ASSERT(acmp->sz == ERTS_MAX_INTERNAL_ATOM_CACHE_ENTRIES
		   || (!(dflags & DFLAG_UTF8_ATOMS)
		       && atom_tab(atom_val(atom))->latin1_chars < 0));
	    return -1;
	}
	else {
	    ASSERT(acmp->cache[ix].iix < ERTS_ATOM_CACHE_SIZE);
	    return acmp->cache[ix].atom == atom ? acmp->cache[ix].iix : -1;
	}
    }
}

void
erts_finalize_atom_cache_map(ErtsAtomCacheMap *acmp, Uint32 dflags)
{
    if (acmp) {
	int utf8_atoms = (int) (dflags & DFLAG_UTF8_ATOMS);
	int long_atoms = 0; /* !0 if one or more atoms are longer than 255. */
	int i;
	int sz;
	int fix_sz
	    = 1 /* VERSION_MAGIC */
	    + 1 /* DIST_HEADER */
	    + 1 /* dist header flags */
	    + 1 /* number of internal cache entries */
	    ;
	int min_sz;
	ASSERT(acmp->hdr_sz < 0);
	/* Make sure cache update instructions fit */
	min_sz = fix_sz+(2+4)*acmp->sz;
	sz = fix_sz;
	for (i = 0; i < acmp->sz; i++) {
	    Atom *a;
	    Eterm atom;
	    int len;
	    atom = acmp->cache[acmp->cix[i]].atom;
	    ASSERT(is_atom(atom));
	    a = atom_tab(atom_val(atom));
	    len = (int) (utf8_atoms ? a->len : a->latin1_chars);
	    ASSERT(len >= 0);
	    if (!long_atoms && len > 255)
		long_atoms = 1;
	    /* Enough for a new atom cache value */
	    sz += 1 /* cix */ + 1 /* length */ + len /* text */;
	}
	if (long_atoms) {
	    acmp->long_atoms = 1;
	    sz += acmp->sz; /* we need 2 bytes per atom for length */
	}
	/* Dynamically sized flag field */
	sz += ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTES(acmp->sz);
	if (sz < min_sz)
	    sz = min_sz;
	acmp->hdr_sz = sz;
    }
}

Uint
erts_encode_ext_dist_header_size(ErtsAtomCacheMap *acmp)
{
    if (!acmp)
	return 0;
    else {
	ASSERT(acmp->hdr_sz >= 0);
	return acmp->hdr_sz;
    }
}

byte *erts_encode_ext_dist_header_setup(byte *ctl_ext, ErtsAtomCacheMap *acmp)
{
    /* Maximum number of atom must be less than the maximum of a 32 bits
       unsigned integer. Check is done in erl_init.c, erl_start function. */
    if (!acmp)
	return ctl_ext;
    else {
	int i;
	byte *ep = ctl_ext;
	byte dist_hdr_flags = acmp->long_atoms ? ERTS_DIST_HDR_LONG_ATOMS_FLG : 0;
	ASSERT(acmp->hdr_sz >= 0);
	/*
	 * Write cache update instructions. Note that this is a purely
	 * internal format, never seen on the wire. This section is later
	 * rewritten by erts_encode_ext_dist_header_finalize() while updating
	 * the cache. We write the header backwards just before the
	 * actual term(s).
	 */
	for (i = acmp->sz-1; i >= 0; i--) {
	    Uint32 aval;
	    ASSERT(0 <= acmp->cix[i] && acmp->cix[i] < ERTS_ATOM_CACHE_SIZE);
	    ASSERT(i == acmp->cache[acmp->cix[i]].iix);
	    ASSERT(is_atom(acmp->cache[acmp->cix[i]].atom));

	    aval = (Uint32) atom_val(acmp->cache[acmp->cix[i]].atom);
	    ep -= 4;
	    put_int32(aval, ep);
	    ep -= 2;
	    put_int16(acmp->cix[i], ep);
	}
	--ep;
	put_int8(acmp->sz, ep);
	--ep;
	put_int8(dist_hdr_flags, ep);
	*--ep = DIST_HEADER;
	*--ep = VERSION_MAGIC;
	return ep;
    }
}

byte *erts_encode_ext_dist_header_finalize(byte *ext, ErtsAtomCache *cache, Uint32 dflags)
{
    byte *ip;
    byte instr_buf[(2+4)*ERTS_ATOM_CACHE_SIZE];
    int ci, sz;
    byte dist_hdr_flags;
    int long_atoms;
    int utf8_atoms = (int) (dflags & DFLAG_UTF8_ATOMS);
    register byte *ep = ext;
    ASSERT(ep[0] == VERSION_MAGIC);
    if (ep[1] != DIST_HEADER)
	return ext;

    dist_hdr_flags = ep[2];
    long_atoms = ERTS_DIST_HDR_LONG_ATOMS_FLG & ((int) dist_hdr_flags);

    /*
     * Update output atom cache and write the external version of
     * the dist header. We write the header backwards just
     * before the actual term(s).
     */
    ep += 3;
    ci = (int) get_int8(ep);
    ASSERT(0 <= ci && ci < ERTS_ATOM_CACHE_SIZE);
    ep += 1;
    sz = (2+4)*ci;
    ip = &instr_buf[0];
    sys_memcpy((void *) ip, (void *) ep, sz);
    ep += sz;
    /* ep now points to the beginning of the control message term */
#ifdef ERTS_DEBUG_USE_DIST_SEP
    ASSERT(*ep == VERSION_MAGIC);
#endif
    if (ci > 0) {
	Uint32 flgs_buf[((ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTES(
			      ERTS_MAX_INTERNAL_ATOM_CACHE_ENTRIES)-1)
			 / sizeof(Uint32))+1];
	register Uint32 flgs;
	int iix, flgs_bytes, flgs_buf_ix, used_half_bytes;
#ifdef DEBUG
	int tot_used_half_bytes;
#endif

	flgs_bytes = ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTES(ci);

	ASSERT(flgs_bytes <= sizeof(flgs_buf));
	flgs = (Uint32) dist_hdr_flags;
	flgs_buf_ix = 0;
	if ((ci & 1) == 0)
	    used_half_bytes = 2;
	else
	    used_half_bytes = 1;
#ifdef DEBUG
	tot_used_half_bytes = used_half_bytes;
#endif
	iix = ci-1;
	while (iix >= 0) {
	    int cix;
	    Eterm atom;

	    if (used_half_bytes != 8)
		flgs <<= 4;
	    else {
		flgs_buf[flgs_buf_ix++] = flgs;
		flgs = 0;
		used_half_bytes = 0;
	    }

	    ip = &instr_buf[0] + (2+4)*iix;
	    cix = (int) get_int16(&ip[0]);
	    ASSERT(0 <= cix && cix < ERTS_ATOM_CACHE_SIZE);
	    atom = make_atom((Uint) get_int32(&ip[2]));
	    if (cache->out_arr[cix] == atom) {
		--ep;
		put_int8(cix, ep);
		flgs |= ((cix >> 8) & 7);
	    }
	    else {
		Atom *a;
		cache->out_arr[cix] = atom;
		a = atom_tab(atom_val(atom));
		if (utf8_atoms) {
		    sz = a->len;
		    ep -= sz;
		    sys_memcpy((void *) ep, (void *) a->name, sz);
		}
		else {
		    ASSERT(0 <= a->latin1_chars && a->latin1_chars <= MAX_ATOM_CHARACTERS);
		    ep -= a->latin1_chars;
		    sz = erts_utf8_to_latin1(ep, a->name, a->len);
		    ASSERT(a->latin1_chars == sz);
		}
		if (long_atoms) {
		    ep -= 2;
		    put_int16(sz, ep);
		}
		else {
		    ASSERT(0 <= sz && sz <= 255);
		    --ep;
		    put_int8(sz, ep);
		}
		--ep;
		put_int8(cix, ep);
		flgs |= (8 | ((cix >> 8) & 7));
	    }
	    iix--;
	    used_half_bytes++;
#ifdef DEBUG
	    tot_used_half_bytes++;
#endif
	}
	ASSERT(tot_used_half_bytes == 2*flgs_bytes);
	flgs_buf[flgs_buf_ix] = flgs;
	flgs_buf_ix = 0;
	while (1) {
	    flgs = flgs_buf[flgs_buf_ix];
	    if (flgs_bytes > 4) {
		*--ep = (byte) ((flgs >> 24) & 0xff);
		*--ep = (byte) ((flgs >> 16) & 0xff);
		*--ep = (byte) ((flgs >> 8) & 0xff);
		*--ep = (byte) (flgs & 0xff);
		flgs_buf_ix++;
		flgs_bytes -= 4;
	    }
	    else {
		switch (flgs_bytes) {
		case 4:
		    *--ep = (byte) ((flgs >> 24) & 0xff);
		case 3:
		    *--ep = (byte) ((flgs >> 16) & 0xff);
		case 2:
		    *--ep = (byte) ((flgs >> 8) & 0xff);
		case 1:
		    *--ep = (byte) (flgs & 0xff);
		}
		break;
	    }
	}
    }
    --ep;
    put_int8(ci, ep);
    *--ep = DIST_HEADER;
    *--ep = VERSION_MAGIC;
    return ep;
}

int erts_encode_dist_ext_size(Eterm term, Uint32 flags, ErtsAtomCacheMap *acmp,
			      Uint* szp)
{
    Uint sz;
    if (encode_size_struct_int(NULL, acmp, term, flags, NULL, &sz)) {
	return -1;
    } else {
#ifndef ERTS_DEBUG_USE_DIST_SEP
	if (!(flags & DFLAG_DIST_HDR_ATOM_CACHE))
#endif
	    sz++ /* VERSION_MAGIC */;

	*szp += sz;
	return 0;
    }
}

int erts_encode_dist_ext_size_int(Eterm term, struct erts_dsig_send_context* ctx, Uint* szp)
{
    Uint sz;
    if (encode_size_struct_int(&ctx->u.sc, ctx->acmp, term, ctx->flags, &ctx->reds, &sz)) {
	return -1;
    } else {
#ifndef ERTS_DEBUG_USE_DIST_SEP
	if (!(ctx->flags & DFLAG_DIST_HDR_ATOM_CACHE))
#endif
	    sz++ /* VERSION_MAGIC */;

	*szp += sz;
	return 0;
    }
}

Uint erts_encode_ext_size(Eterm term)
{
    return encode_size_struct2(NULL, term, TERM_TO_BINARY_DFLAGS)
	+ 1 /* VERSION_MAGIC */;
}

Uint erts_encode_ext_size_2(Eterm term, unsigned dflags)
{
    return encode_size_struct2(NULL, term, dflags)
        + 1 /* VERSION_MAGIC */;
}

Uint erts_encode_ext_size_ets(Eterm term)
{
    return encode_size_struct2(NULL, term, TERM_TO_BINARY_DFLAGS|DFLAG_INTERNAL_TAGS);
}


int erts_encode_dist_ext(Eterm term, byte **ext, Uint32 flags, ErtsAtomCacheMap *acmp,
			  TTBEncodeContext* ctx, Sint* reds)
{
    if (!ctx || !ctx->wstack.wstart) {
    #ifndef ERTS_DEBUG_USE_DIST_SEP
	if (!(flags & DFLAG_DIST_HDR_ATOM_CACHE))
    #endif
	    *(*ext)++ = VERSION_MAGIC;
    }
    return enc_term_int(ctx, acmp, term, *ext, flags, NULL, reds, ext);
}

void erts_encode_ext(Eterm term, byte **ext)
{
    byte *ep = *ext;
    *ep++ = VERSION_MAGIC;
    ep = enc_term(NULL, term, ep, TERM_TO_BINARY_DFLAGS, NULL);
    if (!ep)
	erts_exit(ERTS_ABORT_EXIT,
		 "%s:%d:erts_encode_ext(): Internal data structure error\n",
		 __FILE__, __LINE__);
    *ext = ep;
}

byte* erts_encode_ext_ets(Eterm term, byte *ep, struct erl_off_heap_header** off_heap)
{
    return enc_term(NULL, term, ep, TERM_TO_BINARY_DFLAGS|DFLAG_INTERNAL_TAGS,
		    off_heap);
}

ErtsDistExternal *
erts_make_dist_ext_copy(ErtsDistExternal *edep, Uint xsize)
{
    size_t align_sz;
    size_t dist_ext_sz;
    size_t ext_sz;
    byte *ep;
    ErtsDistExternal *new_edep;

    dist_ext_sz = ERTS_DIST_EXT_SIZE(edep);
    ASSERT(edep->ext_endp && edep->extp);
    ASSERT(edep->ext_endp >= edep->extp);
    ext_sz = edep->ext_endp - edep->extp;

    align_sz = ERTS_EXTRA_DATA_ALIGN_SZ(dist_ext_sz + ext_sz);

    new_edep = erts_alloc(ERTS_ALC_T_EXT_TERM_DATA,
			  dist_ext_sz + ext_sz + align_sz + xsize);

    ep = (byte *) new_edep;
    sys_memcpy((void *) ep, (void *) edep, dist_ext_sz);
    ep += dist_ext_sz;
    if (new_edep->dep)
	erts_smp_refc_inc(&new_edep->dep->refc, 1);
    new_edep->extp = ep;
    new_edep->ext_endp = ep + ext_sz;
    new_edep->heap_size = -1;
    sys_memcpy((void *) ep, (void *) edep->extp, ext_sz);
    return new_edep;
}

int
erts_prepare_dist_ext(ErtsDistExternal *edep,
		      byte *ext,
		      Uint size,
		      DistEntry *dep,
		      ErtsAtomCache *cache)
{
#undef ERTS_EXT_FAIL
#undef ERTS_EXT_HDR_FAIL
#if 1
#define ERTS_EXT_FAIL goto fail
#define ERTS_EXT_HDR_FAIL goto bad_hdr
#else
#define ERTS_EXT_FAIL abort()
#define ERTS_EXT_HDR_FAIL abort()
#endif

    register byte *ep = ext;
    int utf8_atoms = (int) (dep->flags & DFLAG_UTF8_ATOMS);

    edep->heap_size = -1;
    edep->ext_endp = ext+size;

    if (size < 2)
	ERTS_EXT_FAIL;

    if (ep[0] != VERSION_MAGIC) {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	if (dep)
	    erts_dsprintf(dsbufp,
			  "** Got message from incompatible erlang on "
			  "channel %d\n",
			  dist_entry_channel_no(dep));
	else
	    erts_dsprintf(dsbufp,
			  "** Attempt to convert old incompatible "
			  "binary %d\n",
			  *ep);
	erts_send_error_to_logger_nogl(dsbufp);
	ERTS_EXT_FAIL;
    }

    edep->flags = 0;
    edep->dep = dep;
    if (dep) {
	erts_smp_de_rlock(dep);
	if (dep->flags & DFLAG_DIST_HDR_ATOM_CACHE)
	    edep->flags |= ERTS_DIST_EXT_DFLAG_HDR;
	    
	edep->flags |= (dep->connection_id & ERTS_DIST_EXT_CON_ID_MASK);
	erts_smp_de_runlock(dep);
    }

    if (ep[1] != DIST_HEADER) {
	if (edep->flags & ERTS_DIST_EXT_DFLAG_HDR)
	    ERTS_EXT_HDR_FAIL;
	edep->attab.size = 0;
	edep->extp = ext;
    }
    else {
	int tix;
	int no_atoms;

	if (!(edep->flags & ERTS_DIST_EXT_DFLAG_HDR))
	    ERTS_EXT_HDR_FAIL;

#undef CHKSIZE
#define CHKSIZE(SZ) \
	do { if ((SZ) > edep->ext_endp - ep) ERTS_EXT_HDR_FAIL; } while(0)

	CHKSIZE(1+1+1);
	ep += 2;
	no_atoms = (int) get_int8(ep);
	if (no_atoms < 0 || ERTS_ATOM_CACHE_SIZE < no_atoms)
	    ERTS_EXT_HDR_FAIL;
	ep++;
	if (no_atoms) {
	    int long_atoms = 0;
#ifdef DEBUG
	    byte *flgs_buf = ep;
#endif
	    byte *flgsp = ep;
	    int flgs_size = ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTES(no_atoms);
	    int byte_ix;
	    int bit_ix;
	    int got_flgs;
	    register Uint32 flgs = 0;

	    CHKSIZE(flgs_size);
	    ep += flgs_size;

	    /*
	     * Check long atoms flag
	     */
	    byte_ix = ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTE_IX(no_atoms);
	    bit_ix = ERTS_DIST_HDR_ATOM_CACHE_FLAG_BIT_IX(no_atoms);
	    if (flgsp[byte_ix] & (((byte) ERTS_DIST_HDR_LONG_ATOMS_FLG) << bit_ix))
		long_atoms = 1;

#ifdef DEBUG
	    byte_ix = 0;
	    bit_ix = 0;
#endif
	    got_flgs = 0;
	    /*
	     * Setup the atom translation table.
	     */
	    edep->flags |= ERTS_DIST_EXT_ATOM_TRANS_TAB;
	    edep->attab.size = no_atoms;
	    for (tix = 0; tix < no_atoms; tix++) {
		Eterm atom;
		int cix;
		int len;

		if (!got_flgs) {
		    int left = no_atoms - tix;
		    if (left > 6) {
			flgs = ((((Uint32) flgsp[3]) << 24)
		        	| (((Uint32) flgsp[2]) << 16)
				| (((Uint32) flgsp[1]) << 8)
				| ((Uint32) flgsp[0]));
			flgsp += 4;
		    }
		    else {
			flgs = 0;
			switch (left) {
			case 6:
			case 5:
			    flgs |= (((Uint32) flgsp[2]) << 16);
			case 4:
			case 3:
			    flgs |= (((Uint32) flgsp[1]) << 8);
			case 2:
			case 1:
			    flgs |= ((Uint32) flgsp[0]);
			}
		    }
		    got_flgs = 8;
		}

		ASSERT(byte_ix == ERTS_DIST_HDR_ATOM_CACHE_FLAG_BYTE_IX(tix));
		ASSERT(bit_ix == ERTS_DIST_HDR_ATOM_CACHE_FLAG_BIT_IX(tix));
		ASSERT((flgs & 3)
		       == (((flgs_buf[byte_ix]
			     & (((byte) 3) << bit_ix)) >> bit_ix) & 3));

		CHKSIZE(1);
		cix = (int) ((flgs & 7) << 8);
		if ((flgs & 8) == 0) {
		    /* atom already cached */
		    cix += (int) get_int8(ep);
		    if (cix >= ERTS_ATOM_CACHE_SIZE)
			ERTS_EXT_HDR_FAIL;
		    ep++;
		    atom = cache->in_arr[cix];
		    if (!is_atom(atom))
			ERTS_EXT_HDR_FAIL;
		    edep->attab.atom[tix] = atom;
		}
		else {
		    /* new cached atom */
		    cix += (int) get_int8(ep);
		    if (cix >= ERTS_ATOM_CACHE_SIZE)
			ERTS_EXT_HDR_FAIL;
		    ep++;
		    if (long_atoms) {
			CHKSIZE(2);
			len = get_int16(ep);
			ep += 2;
		    }
		    else {
			CHKSIZE(1);
			len = get_int8(ep);
			ep++;
		    }
		    CHKSIZE(len);
		    atom = erts_atom_put((byte *) ep,
					 len,
					 (utf8_atoms
					  ? ERTS_ATOM_ENC_UTF8
					  : ERTS_ATOM_ENC_LATIN1),
					 0);
		    if (is_non_value(atom))
			ERTS_EXT_HDR_FAIL;
		    ep += len;
		    cache->in_arr[cix] = atom;
		    edep->attab.atom[tix] = atom;
		}
		flgs >>= 4;
		got_flgs--;
#ifdef DEBUG
		bit_ix += 4;
		if (bit_ix >= 8) {
		    bit_ix = 0;
		    flgs = (int) flgs_buf[++byte_ix];
		    ASSERT(byte_ix < flgs_size);
		}
#endif
	    }
	}
	edep->extp = ep;
#ifdef ERTS_DEBUG_USE_DIST_SEP
	if (*ep != VERSION_MAGIC)
	    ERTS_EXT_HDR_FAIL;
#endif
    }
#ifdef ERTS_DEBUG_USE_DIST_SEP
    if (*ep != VERSION_MAGIC)
	ERTS_EXT_FAIL;
#endif

    return 0;

#undef CHKSIZE
#undef ERTS_EXT_FAIL
#undef ERTS_EXT_HDR_FAIL

 bad_hdr:
    if (dep) {
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	erts_dsprintf(dsbufp,
		      "%T got a corrupted distribution header from %T "
		      "on distribution channel %d\n",
		      erts_this_node->sysname,
		      edep->dep->sysname,
		      dist_entry_channel_no(edep->dep));
	for (ep = ext; ep < edep->ext_endp; ep++)
	    erts_dsprintf(dsbufp, ep != ext ? ",%b8u" : "<<%b8u", *ep);
	erts_dsprintf(dsbufp, ">>");
	erts_send_warning_to_logger_nogl(dsbufp);
    }
 fail:
    if (dep)
	erts_kill_dist_connection(dep, dep->connection_id);
    return -1;
}

static void
bad_dist_ext(ErtsDistExternal *edep)
{
    if (edep->dep) {
	DistEntry *dep = edep->dep;
	erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
	byte *ep;
	erts_dsprintf(dsbufp,
		      "%T got a corrupted external term from %T "
		      "on distribution channel %d\n",
		      erts_this_node->sysname,
		      dep->sysname,
		      dist_entry_channel_no(dep));
	for (ep = edep->extp; ep < edep->ext_endp; ep++)
	    erts_dsprintf(dsbufp,
			  ep != edep->extp ? ",%b8u" : "<<...,%b8u",
			  *ep);
	erts_dsprintf(dsbufp, ">>\n");
	erts_dsprintf(dsbufp, "ATOM_CACHE_REF translations: ");
	if (!(edep->flags & ERTS_DIST_EXT_ATOM_TRANS_TAB) || !edep->attab.size)
	    erts_dsprintf(dsbufp, "none");
	else {
	    int i;
	    erts_dsprintf(dsbufp, "0=%T", edep->attab.atom[0]);
	    for (i = 1; i < edep->attab.size; i++)
		erts_dsprintf(dsbufp, ", %d=%T", i, edep->attab.atom[i]);
	}
	erts_send_warning_to_logger_nogl(dsbufp);
	erts_kill_dist_connection(dep, ERTS_DIST_EXT_CON_ID(edep));
    }
}

Sint
erts_decode_dist_ext_size(ErtsDistExternal *edep)
{
    Sint res;
    byte *ep;
    if (edep->extp >= edep->ext_endp)
	goto fail;
#ifndef ERTS_DEBUG_USE_DIST_SEP
    if (edep->flags & ERTS_DIST_EXT_DFLAG_HDR) {
	if (*edep->extp == VERSION_MAGIC)
	    goto fail;
	ep = edep->extp;
    }
    else
#endif
    {
	if (*edep->extp != VERSION_MAGIC)
	    goto fail;
	ep = edep->extp+1;
    }
    res = decoded_size(ep, edep->ext_endp, 0, NULL);
    if (res >= 0)
	return res;
 fail:
    bad_dist_ext(edep);
    return -1;
}

Sint erts_decode_ext_size(byte *ext, Uint size)
{
    if (size == 0 || *ext != VERSION_MAGIC)
	return -1;
    return decoded_size(ext+1, ext+size, 0, NULL);
}

Sint erts_decode_ext_size_ets(byte *ext, Uint size)
{
    Sint sz = decoded_size(ext, ext+size, 1, NULL);
    ASSERT(sz >= 0);
    return sz;
}


/*
** hpp is set to either a &p->htop or
** a pointer to a memory pointer (form message buffers)
** on return hpp is updated to point after allocated data
*/
Eterm
erts_decode_dist_ext(ErtsHeapFactory* factory,
		     ErtsDistExternal *edep)
{
    Eterm obj;
    byte* ep = edep->extp;

    if (ep >= edep->ext_endp)
	goto error;
#ifndef ERTS_DEBUG_USE_DIST_SEP
    if (edep->flags & ERTS_DIST_EXT_DFLAG_HDR) {
	if (*ep == VERSION_MAGIC)
	    goto error;
    }
    else
#endif
    {
	if (*ep != VERSION_MAGIC)
	    goto error;
	ep++;
    }
    ep = dec_term(edep, factory, ep, &obj, NULL);
    if (!ep)
	goto error;

    edep->extp = ep;

    return obj;

 error:
    erts_factory_undo(factory);

    bad_dist_ext(edep);

    return THE_NON_VALUE;
}

Eterm erts_decode_ext(ErtsHeapFactory* factory, byte **ext, Uint32 flags)
{
    ErtsDistExternal ede, *edep;
    Eterm obj;
    byte *ep = *ext;
    if (*ep++ != VERSION_MAGIC) {
        erts_factory_undo(factory);
	return THE_NON_VALUE;
    }
    if (flags) {
        ASSERT(flags == ERTS_DIST_EXT_BTT_SAFE);
        ede.flags = flags; /* a dummy struct just for the flags */
        edep = &ede;
    } else {
        edep = NULL;
    }
    ep = dec_term(edep, factory, ep, &obj, NULL);
    if (!ep) {
	return THE_NON_VALUE;
    }
    *ext = ep;
    return obj;
}

Eterm erts_decode_ext_ets(ErtsHeapFactory* factory, byte *ext)
{
    Eterm obj;
    ext = dec_term(NULL, factory, ext, &obj, NULL);
    ASSERT(ext);
    return obj;
}

/**********************************************************************/

BIF_RETTYPE erts_debug_dist_ext_to_term_2(BIF_ALIST_2)
{
    ErtsHeapFactory factory;
    Eterm res;
    Sint hsz;
    ErtsDistExternal ede;
    Eterm *tp;
    Eterm real_bin;
    Uint offset;
    Uint size;
    Uint bitsize;
    Uint bitoffs;
    Uint arity;
    int i;

    ede.flags = ERTS_DIST_EXT_ATOM_TRANS_TAB;
    ede.dep = NULL;
    ede.heap_size = -1;
    
    if (is_not_tuple(BIF_ARG_1))
	goto badarg;
    tp = tuple_val(BIF_ARG_1);
    arity = arityval(tp[0]);
    if (arity > ERTS_MAX_INTERNAL_ATOM_CACHE_ENTRIES)
	goto badarg;

    ede.attab.size = arity;
    for (i = 1; i <= arity; i++) {
	if (is_not_atom(tp[i]))
	    goto badarg;
	ede.attab.atom[i-1] = tp[i];
    }

    if (is_not_binary(BIF_ARG_2))
	goto badarg;

    size = binary_size(BIF_ARG_2);
    if (size == 0)
	goto badarg;
    ERTS_GET_REAL_BIN(BIF_ARG_2, real_bin, offset, bitoffs, bitsize);
    if (bitsize != 0)
	goto badarg;

    ede.extp = binary_bytes(real_bin)+offset;
    ede.ext_endp = ede.extp + size;

    hsz = erts_decode_dist_ext_size(&ede);
    if (hsz < 0)
	goto badarg;

    erts_factory_proc_prealloc_init(&factory, BIF_P, hsz);
    res = erts_decode_dist_ext(&factory, &ede);
    erts_factory_close(&factory);

    if (is_value(res))
	BIF_RET(res);

 badarg:

    BIF_ERROR(BIF_P, BADARG);
}

static BIF_RETTYPE term_to_binary_trap_1(BIF_ALIST_1)
{
    Eterm *tp = tuple_val(BIF_ARG_1);
    Eterm Term = tp[1];
    Eterm bt = tp[2];
    Binary *bin = erts_magic_ref2bin(bt);
    Eterm res = erts_term_to_binary_int(BIF_P, Term, 0, 0,bin);
    if (is_tuple(res)) {
	ASSERT(BIF_P->flags & F_DISABLE_GC);
	BIF_TRAP1(&term_to_binary_trap_export,BIF_P,res);
    } else {
        if (erts_set_gc_state(BIF_P, 1)
            || MSO(BIF_P).overhead > BIN_VHEAP_SZ(BIF_P))
            ERTS_BIF_YIELD_RETURN(BIF_P, res);
        else
            BIF_RET(res);
    }
}

HIPE_WRAPPER_BIF_DISABLE_GC(term_to_binary, 1)

BIF_RETTYPE term_to_binary_1(BIF_ALIST_1)
{
    Eterm res = erts_term_to_binary_int(BIF_P, BIF_ARG_1, 0, TERM_TO_BINARY_DFLAGS, NULL);
    if (is_tuple(res)) {
	erts_set_gc_state(BIF_P, 0);
	BIF_TRAP1(&term_to_binary_trap_export,BIF_P,res);
    } else {
	ASSERT(!(BIF_P->flags & F_DISABLE_GC));
	BIF_RET(res);
    }
}

HIPE_WRAPPER_BIF_DISABLE_GC(term_to_binary, 2)

BIF_RETTYPE term_to_binary_2(BIF_ALIST_2)
{
    Process* p = BIF_P;
    Eterm Term = BIF_ARG_1;
    Eterm Flags = BIF_ARG_2;
    int level = 0;
    Uint flags = TERM_TO_BINARY_DFLAGS;
    Eterm res;

    while (is_list(Flags)) {
	Eterm arg = CAR(list_val(Flags));
	Eterm* tp;
	if (arg == am_compressed) {
	    level = Z_DEFAULT_COMPRESSION;
	} else if (is_tuple(arg) && *(tp = tuple_val(arg)) == make_arityval(2)) {
	    if (tp[1] == am_minor_version && is_small(tp[2])) {
		switch (signed_val(tp[2])) {
		case 0:
		    flags = TERM_TO_BINARY_DFLAGS & ~DFLAG_NEW_FLOATS;
		    break;
		case 1:
		    flags = TERM_TO_BINARY_DFLAGS;
		    break;
		default:
		    goto error;
		}
	    } else if (tp[1] == am_compressed && is_small(tp[2])) {
		level = signed_val(tp[2]);
		if (!(0 <= level && level < 10)) {
		    goto error;
		}
	    } else {
		goto error;
	    }
	} else {
	error:
	    BIF_ERROR(p, BADARG);
	}
	Flags = CDR(list_val(Flags));
    }
    if (is_not_nil(Flags)) {
	goto error;
    }

    res = erts_term_to_binary_int(p, Term, level, flags, NULL);
    if (is_tuple(res)) {
	erts_set_gc_state(p, 0);
	BIF_TRAP1(&term_to_binary_trap_export,BIF_P,res);
    } else {
	ASSERT(!(BIF_P->flags & F_DISABLE_GC));
	BIF_RET(res);
    }
}


enum B2TState { /* order is somewhat significant */
    B2TPrepare,
    B2TUncompressChunk,
    B2TSizeInit,
    B2TSize,
    B2TDecodeInit,
    B2TDecode,
    B2TDecodeList,
    B2TDecodeTuple,
    B2TDecodeString,
    B2TDecodeBinary,

    B2TDone,
    B2TDecodeFail,
    B2TBadArg
};

typedef struct {
    int heap_size;
    int terms;
    byte* ep;
    int atom_extra_skip;
} B2TSizeContext;

typedef struct {
    byte*  ep;
    Eterm  res;
    Eterm* next;
    ErtsHeapFactory factory;
    int remaining_n;
    char* remaining_bytes;
    ErtsWStack flat_maps;
    ErtsPStack hamt_array;
} B2TDecodeContext;

typedef struct {
    z_stream stream;
    byte* dbytes;
    Uint dleft;
} B2TUncompressContext;

typedef struct B2TContext_t {
    Sint heap_size;
    byte* aligned_alloc;
    ErtsBinary2TermState b2ts;
    Uint32 flags;
    SWord reds;
    Eterm trap_bin;
    Export *bif;
    Eterm arg[2];
    enum B2TState state;
    union {
	B2TSizeContext sc;
	B2TDecodeContext dc;
	B2TUncompressContext uc;
    } u;
} B2TContext;

static B2TContext* b2t_export_context(Process*, B2TContext* src);

static uLongf binary2term_uncomp_size(byte* data, Sint size)
{
    z_stream stream;
    int err;
    const uInt chunk_size = 64*1024;  /* Ask tmp-alloc about a suitable size? */
    void* tmp_buf = erts_alloc(ERTS_ALC_T_TMP, chunk_size);
    uLongf uncomp_size = 0;

    stream.next_in = (Bytef*)data;
    stream.avail_in = (uInt)size;
    stream.next_out = tmp_buf;
    stream.avail_out = (uInt)chunk_size;

    erl_zlib_alloc_init(&stream);

    err = inflateInit(&stream);
    if (err == Z_OK) {
	do {
	    stream.next_out = tmp_buf;
	    stream.avail_out = chunk_size;	   
	    err = inflate(&stream, Z_NO_FLUSH);
	    uncomp_size += chunk_size - stream.avail_out;
	}while (err == Z_OK);
	inflateEnd(&stream);
    }
    erts_free(ERTS_ALC_T_TMP, tmp_buf);
    return err == Z_STREAM_END ? uncomp_size : 0;
}

static ERTS_INLINE int
binary2term_prepare(ErtsBinary2TermState *state, byte *data, Sint data_size,
		    B2TContext** ctxp, Process* p)
{
    byte *bytes = data;
    Sint size = data_size;

    state->exttmp = 0;

    if (size < 1 || *bytes != VERSION_MAGIC) {
	return -1;
    }
    bytes++;
    size--;
    if (size < 5 || *bytes != COMPRESSED) {
	state->extp = bytes;
        if (ctxp)
	    (*ctxp)->state = B2TSizeInit;
    }
    else  {
	uLongf dest_len = (Uint32) get_int32(bytes+1);
	bytes += 5;
	size -= 5;	
	if (dest_len > 32*1024*1024
	    || (state->extp = erts_alloc_fnf(ERTS_ALC_T_EXT_TERM_DATA, dest_len)) == NULL) {
            /*
             * Try avoid out-of-memory crash due to corrupted 'dest_len'
             * by checking the actual length of the uncompressed data.
             * The only way to do that is to uncompress it. Sad but true.
             */
	    if (dest_len != binary2term_uncomp_size(bytes, size)) {
                return -1;
	    }
	    state->extp = erts_alloc(ERTS_ALC_T_EXT_TERM_DATA, dest_len);
            if (ctxp)
                (*ctxp)->reds -= dest_len;
	}
	state->exttmp = 1;
        if (ctxp) {
            /*
             * Start decompression by exporting trap context
             * so we don't have to deal with deep-copying z_stream.
             */
            B2TContext* ctx = b2t_export_context(p, *ctxp);
            ASSERT(state = &(*ctxp)->b2ts);
            state = &ctx->b2ts;

	    if (erl_zlib_inflate_start(&ctx->u.uc.stream, bytes, size) != Z_OK)
		return -1;

	    ctx->u.uc.dbytes = state->extp;
	    ctx->u.uc.dleft = dest_len;
	    ctx->state = B2TUncompressChunk;
            *ctxp = ctx;
        }
	else {
	    uLongf dlen = dest_len;
	    if (erl_zlib_uncompress(state->extp, &dlen, bytes, size) != Z_OK
		|| dlen != dest_len) {
		return -1;
	    }
        }
	size = (Sint) dest_len;
    }
    state->extsize = size;
    return 0;
}

static ERTS_INLINE void
binary2term_abort(ErtsBinary2TermState *state)
{
    if (state->exttmp) {
	state->exttmp = 0;
	erts_free(ERTS_ALC_T_EXT_TERM_DATA, state->extp);
    }
}

static ERTS_INLINE Eterm
binary2term_create(ErtsDistExternal *edep, ErtsBinary2TermState *state,
		   ErtsHeapFactory* factory)
{
    Eterm res;

    if (!dec_term(edep, factory, state->extp, &res, NULL))
	res = THE_NON_VALUE;
    if (state->exttmp) {
	state->exttmp = 0;
	erts_free(ERTS_ALC_T_EXT_TERM_DATA, state->extp);
    }
    return res;
}

Sint
erts_binary2term_prepare(ErtsBinary2TermState *state, byte *data, Sint data_size)
{
    Sint res;

    if (binary2term_prepare(state, data, data_size, NULL, NULL) < 0 ||
        (res=decoded_size(state->extp, state->extp + state->extsize, 0, NULL)) < 0) {

        if (state->exttmp)
            erts_free(ERTS_ALC_T_EXT_TERM_DATA, state->extp);
        state->extp = NULL;
	state->exttmp = 0;
	return -1;
    }
    return res;
}

void
erts_binary2term_abort(ErtsBinary2TermState *state)
{
    binary2term_abort(state);
}

Eterm
erts_binary2term_create(ErtsBinary2TermState *state, ErtsHeapFactory* factory)
{
    return binary2term_create(NULL,state, factory);
}

static void b2t_destroy_context(B2TContext* context)
{
    erts_free_aligned_binary_bytes_extra(context->aligned_alloc,
                                         ERTS_ALC_T_EXT_TERM_DATA);
    context->aligned_alloc = NULL;
    binary2term_abort(&context->b2ts);
    switch (context->state) {
    case B2TUncompressChunk:
	erl_zlib_inflate_finish(&context->u.uc.stream);
	break;
    case B2TDecode:
    case B2TDecodeList:
    case B2TDecodeTuple:
    case B2TDecodeString:
    case B2TDecodeBinary:
	if (context->u.dc.hamt_array.pstart) {
	    erts_free(context->u.dc.hamt_array.alloc_type,
		      context->u.dc.hamt_array.pstart);
	}
	break;
    default:;
    }
}

static void b2t_context_destructor(Binary *context_bin)
{
    B2TContext* ctx = (B2TContext*) ERTS_MAGIC_BIN_DATA(context_bin);
    ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(context_bin) == b2t_context_destructor);

    b2t_destroy_context(ctx);
}

static BIF_RETTYPE binary_to_term_trap_1(BIF_ALIST_1)
{
    Binary *context_bin = erts_magic_ref2bin(BIF_ARG_1);
    ASSERT(ERTS_MAGIC_BIN_DESTRUCTOR(context_bin) == b2t_context_destructor);

    return binary_to_term_int(BIF_P, 0, THE_NON_VALUE, context_bin, NULL,
			      THE_NON_VALUE, THE_NON_VALUE);
}


#define B2T_BYTES_PER_REDUCTION 128
#define B2T_MEMCPY_FACTOR 8

/* Define for testing */
/*#define EXTREME_B2T_TRAPPING 1*/

#ifdef EXTREME_B2T_TRAPPING
static unsigned b2t_rand(void)
{
    static unsigned prev = 17;
    prev = (prev * 214013 + 2531011);
    return prev;
}
#endif


static B2TContext* b2t_export_context(Process* p, B2TContext* src)
{
    Binary* context_b = erts_create_magic_binary(sizeof(B2TContext),
                                                 b2t_context_destructor);
    B2TContext* ctx = ERTS_MAGIC_BIN_DATA(context_b);
    Eterm* hp;
    sys_memcpy(ctx, src, sizeof(B2TContext));
    if (ctx->state >= B2TDecode && ctx->u.dc.next == &src->u.dc.res) {
        ctx->u.dc.next = &ctx->u.dc.res;
    }
    hp = HAlloc(p, ERTS_MAGIC_REF_THING_SIZE);
    ctx->trap_bin = erts_mk_magic_ref(&hp, &MSO(p), context_b);
    return ctx;
}

static BIF_RETTYPE binary_to_term_int(Process* p, Uint32 flags, Eterm bin, Binary* context_b,
				      Export *bif_init, Eterm arg0, Eterm arg1)
{
    BIF_RETTYPE ret_val;
#ifdef EXTREME_B2T_TRAPPING
    SWord initial_reds = 1 + b2t_rand() % 4;
#else
    SWord initial_reds = (Uint)(ERTS_BIF_REDS_LEFT(p) * B2T_BYTES_PER_REDUCTION);
#endif
    B2TContext c_buff;
    B2TContext *ctx;
    int is_first_call;

    if (context_b == NULL) {
	/* Setup enough to get started */
        is_first_call = 1;
        ctx = &c_buff;
	ctx->state = B2TPrepare;
        ctx->aligned_alloc = NULL;
        ctx->flags = flags;
	ctx->bif = bif_init;
	ctx->arg[0] = arg0;
	ctx->arg[1] = arg1;
        IF_DEBUG(ctx->trap_bin = THE_NON_VALUE;)
    } else {
        is_first_call = 0;
	ctx = ERTS_MAGIC_BIN_DATA(context_b);
        ASSERT(ctx->state != B2TPrepare);
    }
    ctx->reds = initial_reds;

    do {
        switch (ctx->state) {
        case B2TPrepare: {
	    byte* bytes;
            Uint bin_size;
            bytes = erts_get_aligned_binary_bytes_extra(bin,
                                                        &ctx->aligned_alloc,
                                                        ERTS_ALC_T_EXT_TERM_DATA,
                                                        0);
            if (bytes == NULL) {
                ctx->b2ts.exttmp = 0;
                ctx->state = B2TBadArg;
                break;
            }
            bin_size = binary_size(bin);
            if (ctx->aligned_alloc) {
                ctx->reds -= bin_size / 8;
            }
            if (binary2term_prepare(&ctx->b2ts, bytes, bin_size, &ctx, p) < 0) {
		ctx->state = B2TBadArg;
	    }
            break;
        }
	case B2TUncompressChunk: {
            uLongf chunk = ctx->reds;
            int zret;

            if (chunk > ctx->u.uc.dleft)
                chunk = ctx->u.uc.dleft;
            zret = erl_zlib_inflate_chunk(&ctx->u.uc.stream,
                                          ctx->u.uc.dbytes, &chunk);
            ctx->u.uc.dbytes += chunk;
            ctx->u.uc.dleft  -= chunk;
            if (zret == Z_OK && ctx->u.uc.dleft > 0) {
                ctx->reds = 0;
            }
            else if (erl_zlib_inflate_finish(&ctx->u.uc.stream) == Z_OK
                     && zret == Z_STREAM_END
                     && ctx->u.uc.dleft == 0) {
                ctx->reds -= chunk;
                ctx->state = B2TSizeInit;
            }
            else {
                ctx->state = B2TBadArg;
            }
            break;
        }
	case B2TSizeInit:
	    ctx->u.sc.ep = NULL;
	    ctx->state = B2TSize;
	    /*fall through*/
        case B2TSize:
            ctx->heap_size = decoded_size(ctx->b2ts.extp,
					  ctx->b2ts.extp + ctx->b2ts.extsize,
                                          0, ctx);
            break;

        case B2TDecodeInit:
            if (ctx == &c_buff && ctx->b2ts.extsize > ctx->reds) {
                /* dec_term will maybe trap, allocate space for magic bin
                   before result term to make it easy to trim with HRelease.
                 */
                ctx = b2t_export_context(p, &c_buff);
            }
            ctx->u.dc.ep = ctx->b2ts.extp;
            ctx->u.dc.res = (Eterm) (UWord) NULL;
            ctx->u.dc.next = &ctx->u.dc.res;
	    erts_factory_proc_prealloc_init(&ctx->u.dc.factory, p, ctx->heap_size);
	    ctx->u.dc.flat_maps.wstart = NULL;
	    ctx->u.dc.hamt_array.pstart = NULL;
            ctx->state = B2TDecode;
            /*fall through*/
	case B2TDecode:
        case B2TDecodeList:
        case B2TDecodeTuple:
        case B2TDecodeString:
        case B2TDecodeBinary: {
	    ErtsDistExternal fakedep;
            fakedep.flags = ctx->flags;
            dec_term(&fakedep, NULL, NULL, NULL, ctx);
            break;
	}
        case B2TDecodeFail:
            /*fall through*/
        case B2TBadArg:
            BUMP_REDS(p, (initial_reds - ctx->reds) / B2T_BYTES_PER_REDUCTION);

	    ASSERT(ctx->bif == bif_export[BIF_binary_to_term_1]
		   || ctx->bif == bif_export[BIF_binary_to_term_2]);

	    if (is_first_call)
		ERTS_BIF_PREP_ERROR(ret_val, p, BADARG);
	    else {
                erts_set_gc_state(p, 1);
		if (is_non_value(ctx->arg[1]))
		    ERTS_BIF_PREP_ERROR_TRAPPED1(ret_val, p, BADARG, ctx->bif,
						 ctx->arg[0]);
		else
		    ERTS_BIF_PREP_ERROR_TRAPPED2(ret_val, p, BADARG, ctx->bif,
						 ctx->arg[0], ctx->arg[1]);
	    }
            b2t_destroy_context(ctx);
	    return ret_val;

        case B2TDone:
            b2t_destroy_context(ctx);

            if (ctx->u.dc.factory.hp > ctx->u.dc.factory.hp_end) {
                erts_exit(ERTS_ERROR_EXIT, ":%s, line %d: heap overrun by %d words(s)\n",
                         __FILE__, __LINE__, ctx->u.dc.factory.hp - ctx->u.dc.factory.hp_end);
            }
	    erts_factory_close(&ctx->u.dc.factory);

            if (!is_first_call) {
                erts_set_gc_state(p, 1);
            }
            BUMP_REDS(p, (initial_reds - ctx->reds) / B2T_BYTES_PER_REDUCTION);
	    ERTS_BIF_PREP_RET(ret_val, ctx->u.dc.res);
	    return ret_val;

        default:
            ASSERT(!"Unknown state in binary_to_term");
        }
    }while (ctx->reds > 0 || ctx->state >= B2TDone);

    if (ctx == &c_buff) {
        ASSERT(ctx->trap_bin == THE_NON_VALUE);
        ctx = b2t_export_context(p, &c_buff);
    }
    ASSERT(ctx->trap_bin != THE_NON_VALUE);

    if (is_first_call) {
        erts_set_gc_state(p, 0);
    }
    BUMP_ALL_REDS(p);

    ERTS_BIF_PREP_TRAP1(ret_val, &binary_to_term_trap_export,
			p, ctx->trap_bin);

    return ret_val;
}

HIPE_WRAPPER_BIF_DISABLE_GC(binary_to_term, 1)

BIF_RETTYPE binary_to_term_1(BIF_ALIST_1)
{
    return binary_to_term_int(BIF_P, 0, BIF_ARG_1, NULL, bif_export[BIF_binary_to_term_1],
			      BIF_ARG_1, THE_NON_VALUE);
}

HIPE_WRAPPER_BIF_DISABLE_GC(binary_to_term, 2)

BIF_RETTYPE binary_to_term_2(BIF_ALIST_2)
{
    Eterm opts;
    Eterm opt;
    Uint32 flags = 0;

    opts = BIF_ARG_2;
    while (is_list(opts)) {
        opt = CAR(list_val(opts));
        if (opt == am_safe) {
            flags |= ERTS_DIST_EXT_BTT_SAFE;
        }
	else {
            goto error;
        }
        opts = CDR(list_val(opts));
    }

    if (is_not_nil(opts))
        goto error;

    return binary_to_term_int(BIF_P, flags, BIF_ARG_1, NULL, bif_export[BIF_binary_to_term_2],
			      BIF_ARG_1, BIF_ARG_2);

error:
    BIF_ERROR(BIF_P, BADARG);
}

Eterm
external_size_1(BIF_ALIST_1)
{
    Process* p = BIF_P;
    Eterm Term = BIF_ARG_1;

    Uint size = erts_encode_ext_size(Term);
    if (IS_USMALL(0, size)) {
	BIF_RET(make_small(size));
    } else {
	Eterm* hp = HAlloc(p, BIG_UINT_HEAP_SIZE);
	BIF_RET(uint_to_big(size, hp));
    }
}

Eterm
external_size_2(BIF_ALIST_2)
{
    Uint size;
    Uint flags = TERM_TO_BINARY_DFLAGS;

    while (is_list(BIF_ARG_2)) {
        Eterm arg = CAR(list_val(BIF_ARG_2));
        Eterm* tp;

        if (is_tuple(arg) && *(tp = tuple_val(arg)) == make_arityval(2)) {
            if (tp[1] == am_minor_version && is_small(tp[2])) {
                switch (signed_val(tp[2])) {
                case 0:
                    flags &= ~DFLAG_NEW_FLOATS;
                    break;
                case 1:
                    break;
                default:
                    goto error;
                }
            } else {
                goto error;
            }
        } else {
        error:
            BIF_ERROR(BIF_P, BADARG);
        }
        BIF_ARG_2 = CDR(list_val(BIF_ARG_2));
    }
    if (is_not_nil(BIF_ARG_2)) {
        goto error;
    }

    size = erts_encode_ext_size_2(BIF_ARG_1, flags);
    if (IS_USMALL(0, size)) {
        BIF_RET(make_small(size));
    } else {
        Eterm* hp = HAlloc(BIF_P, BIG_UINT_HEAP_SIZE);
        BIF_RET(uint_to_big(size, hp));
    }
}

static Eterm
erts_term_to_binary_simple(Process* p, Eterm Term, Uint size, int level, Uint flags)
{
    Eterm bin;
    size_t real_size;
    byte* endp;

    if (level != 0) {
	byte buf[256];
	byte* bytes = buf;
	byte* out_bytes;
	uLongf dest_len;

	if (sizeof(buf) < size) {
	    bytes = erts_alloc(ERTS_ALC_T_TMP, size);
	}

	if ((endp = enc_term(NULL, Term, bytes, flags, NULL))
	    == NULL) {
	    erts_exit(ERTS_ERROR_EXIT, "%s, line %d: bad term: %x\n",
		     __FILE__, __LINE__, Term);
	}
	real_size = endp - bytes;
	if (real_size > size) {
	    erts_exit(ERTS_ERROR_EXIT, "%s, line %d: buffer overflow: %d word(s)\n",
		     __FILE__, __LINE__, real_size - size);
	}

	/*
	 * We don't want to compress if compression actually increases the size.
	 * Therefore, don't give zlib more out buffer than the size of the
	 * uncompressed external format (minus the 5 bytes needed for the
	 * COMPRESSED tag). If zlib returns any error, we'll revert to using
	 * the original uncompressed external term format.
	 */

	if (real_size < 5) {
	    dest_len = 0;
	} else {
	    dest_len = real_size - 5;
	}
	bin = new_binary(p, NULL, real_size+1);
	out_bytes = binary_bytes(bin);
	out_bytes[0] = VERSION_MAGIC;
	if (erl_zlib_compress2(out_bytes+6, &dest_len, bytes, real_size, level) != Z_OK) {
	    sys_memcpy(out_bytes+1, bytes, real_size);
	    bin = erts_realloc_binary(bin, real_size+1);
	} else {
	    out_bytes[1] = COMPRESSED;
	    put_int32(real_size, out_bytes+2);
	    bin = erts_realloc_binary(bin, dest_len+6);
	}
	if (bytes != buf) {
	    erts_free(ERTS_ALC_T_TMP, bytes);
	}
	return bin;
    } else {
	byte* bytes;

	bin = new_binary(p, (byte *)NULL, size);
	bytes = binary_bytes(bin);
	bytes[0] = VERSION_MAGIC;
	if ((endp = enc_term(NULL, Term, bytes+1, flags, NULL))
	    == NULL) {
	    erts_exit(ERTS_ERROR_EXIT, "%s, line %d: bad term: %x\n",
		     __FILE__, __LINE__, Term);
	}
	real_size = endp - bytes;
	if (real_size > size) {
	    erts_exit(ERTS_ERROR_EXIT, "%s, line %d: buffer overflow: %d word(s)\n",
		     __FILE__, __LINE__, endp - (bytes + size));
	}
	return erts_realloc_binary(bin, real_size);
    }
}

Eterm
erts_term_to_binary(Process* p, Eterm Term, int level, Uint flags) {
    Uint size;
    size = encode_size_struct2(NULL, Term, flags) + 1 /* VERSION_MAGIC */;
    return erts_term_to_binary_simple(p, Term, size, level, flags);
}

/* Define EXTREME_TTB_TRAPPING for testing in dist.h */

#ifndef EXTREME_TTB_TRAPPING
#define TERM_TO_BINARY_COMPRESS_CHUNK (1 << 18)
#else
#define TERM_TO_BINARY_COMPRESS_CHUNK 10
#endif
#define TERM_TO_BINARY_MEMCPY_FACTOR 8

static void ttb_context_destructor(Binary *context_bin)
{
    TTBContext *context = ERTS_MAGIC_BIN_DATA(context_bin);
    if (context->alive) {
	context->alive = 0;
	switch (context->state) {
	case TTBSize:
	    DESTROY_SAVED_WSTACK(&context->s.sc.wstack);
	    break;
	case TTBEncode:
	    DESTROY_SAVED_WSTACK(&context->s.ec.wstack);
	    if (context->s.ec.result_bin != NULL) { /* Set to NULL if ever made alive! */
		ASSERT(erts_refc_read(&(context->s.ec.result_bin->refc),0) == 0);
		erts_bin_free(context->s.ec.result_bin);
		context->s.ec.result_bin = NULL;
	    }
	    break;
	case TTBCompress:
	    erl_zlib_deflate_finish(&(context->s.cc.stream));

	    if (context->s.cc.destination_bin != NULL) { /* Set to NULL if ever made alive! */
		ASSERT(erts_refc_read(&(context->s.cc.destination_bin->refc),0) == 0);
		erts_bin_free(context->s.cc.destination_bin);
		context->s.cc.destination_bin = NULL;
	    }
	    
	    if (context->s.cc.result_bin != NULL) { /* Set to NULL if ever made alive! */
		ASSERT(erts_refc_read(&(context->s.cc.result_bin->refc),0) == 0);
		erts_bin_free(context->s.cc.result_bin);
		context->s.cc.result_bin = NULL;
	    }
	    break;
	}
    }
}

static Eterm erts_term_to_binary_int(Process* p, Eterm Term, int level, Uint flags, 
				     Binary *context_b) 
{
    Eterm *hp;
    Eterm res;
    Eterm c_term;
#ifndef EXTREME_TTB_TRAPPING
    Sint reds = (Sint) (ERTS_BIF_REDS_LEFT(p) * TERM_TO_BINARY_LOOP_FACTOR);
#else
    Sint reds = 20; /* For testing */
#endif
    Sint initial_reds = reds; 
    TTBContext c_buff;
    TTBContext *context = &c_buff;

#define EXPORT_CONTEXT()						\
    do {								\
	if (context_b == NULL) {					\
	    context_b = erts_create_magic_binary(sizeof(TTBContext),    \
                                                 ttb_context_destructor);   \
	    context =  ERTS_MAGIC_BIN_DATA(context_b);			\
	    memcpy(context,&c_buff,sizeof(TTBContext));			\
	}								\
    } while (0)

#define RETURN_STATE()							\
    do {								\
	hp = HAlloc(p, ERTS_MAGIC_REF_THING_SIZE+3);                    \
	c_term = erts_mk_magic_ref(&hp, &MSO(p), context_b);            \
	res = TUPLE2(hp, Term, c_term);					\
	BUMP_ALL_REDS(p);                                               \
	return res;							\
    } while (0);


    if (context_b == NULL) {
	/* Setup enough to get started */
	context->state = TTBSize;
	context->alive = 1;
	context->s.sc.wstack.wstart = NULL;
	context->s.sc.flags = flags;
	context->s.sc.level = level;
    } else {
	context = ERTS_MAGIC_BIN_DATA(context_b);
    }	    
    /* Initialization done, now we will go through the states */
    for (;;) {
	switch (context->state) {
	case TTBSize:
	    {
		Uint size;
		Binary *result_bin;
		int level;
		Uint flags;
		/* Try for fast path */
		if (encode_size_struct_int(&context->s.sc, NULL, Term,
					   context->s.sc.flags, &reds, &size) < 0) {
		    EXPORT_CONTEXT();
		    /* Same state */
		    RETURN_STATE();
		}
		++size; /* VERSION_MAGIC */
		/* Move these to next state */
		flags = context->s.sc.flags;
		level = context->s.sc.level;
		if (size <=  ERL_ONHEAP_BIN_LIMIT) {
		    /* Finish in one go */
		    res = erts_term_to_binary_simple(p, Term, size, 
						     level, flags);
		    BUMP_REDS(p, 1);
		    return res;
		}

		result_bin = erts_bin_nrml_alloc(size);
		erts_refc_init(&result_bin->refc, 0);
		result_bin->orig_bytes[0] = VERSION_MAGIC;
		/* Next state immediately, no need to export context */
		context->state = TTBEncode;
		context->s.ec.flags = flags;
		context->s.ec.level = level;
		context->s.ec.wstack.wstart = NULL;
		context->s.ec.result_bin = result_bin;
		break;
	    }
	case TTBEncode:
	    {
		byte *endp;
		byte *bytes = (byte *) context->s.ec.result_bin->orig_bytes;
		size_t real_size;
		Binary *result_bin;

		flags = context->s.ec.flags;
		if (enc_term_int(&context->s.ec, NULL,Term, bytes+1, flags, NULL, &reds, &endp) < 0) {
		    EXPORT_CONTEXT();
		    RETURN_STATE();
		}
		real_size = endp - bytes;
		result_bin = erts_bin_realloc(context->s.ec.result_bin,real_size);
		level = context->s.ec.level;
		BUMP_REDS(p, (initial_reds - reds) / TERM_TO_BINARY_LOOP_FACTOR);
		if (level == 0 || real_size < 6) { /* We are done */
		    ProcBin* pb;
		return_normal:
		    context->s.ec.result_bin = NULL;
		    context->alive = 0;
		    pb = (ProcBin *) HAlloc(p, PROC_BIN_SIZE);
		    pb->thing_word = HEADER_PROC_BIN;
		    pb->size = real_size;
		    pb->next = MSO(p).first;
		    MSO(p).first = (struct erl_off_heap_header*)pb;
		    pb->val = result_bin;
		    pb->bytes = (byte*) result_bin->orig_bytes;
		    pb->flags = 0;
		    OH_OVERHEAD(&(MSO(p)), pb->size / sizeof(Eterm));
		    erts_refc_inc(&result_bin->refc, 1);
		    if (context_b && erts_refc_read(&context_b->refc,0) == 0) {
			erts_bin_free(context_b);
		    }
		    return make_binary(pb);
		}
		/* Continue with compression... */
		/* To make absolutely sure that zlib does not barf on a reallocated context, 
		   we make sure it's "exported" before doing anything compession-like */
		EXPORT_CONTEXT();
		bytes = (byte *) result_bin->orig_bytes; /* result_bin is reallocated */
		if (erl_zlib_deflate_start(&(context->s.cc.stream),bytes+1,real_size-1,level) 
		    != Z_OK) {
		    goto return_normal;
		}
		context->state = TTBCompress;
		context->s.cc.real_size = real_size;
		context->s.cc.result_bin = result_bin;

		result_bin = erts_bin_nrml_alloc(real_size);
		erts_refc_init(&result_bin->refc, 0);
		result_bin->orig_bytes[0] = VERSION_MAGIC;

		context->s.cc.destination_bin = result_bin;
		context->s.cc.dest_len = 0;
		context->s.cc.dbytes = (byte *) result_bin->orig_bytes+6;
		break;
	    }
	case TTBCompress:
	    {
		uLongf tot_dest_len = context->s.cc.real_size - 6;
		uLongf left = (tot_dest_len - context->s.cc.dest_len);
		uLongf this_time = (left > TERM_TO_BINARY_COMPRESS_CHUNK) ?  
		    TERM_TO_BINARY_COMPRESS_CHUNK : 
		    left;
		Binary *result_bin;
		ProcBin *pb;
		Uint max = (ERTS_BIF_REDS_LEFT(p) *  TERM_TO_BINARY_COMPRESS_CHUNK) / CONTEXT_REDS;

		if (max < this_time) {
		    this_time = max + 1; /* do not set this_time to 0 */
		}

		res = erl_zlib_deflate_chunk(&(context->s.cc.stream), context->s.cc.dbytes, &this_time);
		context->s.cc.dbytes += this_time;
		context->s.cc.dest_len += this_time;
		switch (res) {
		case Z_OK:
		    if (context->s.cc.dest_len >= tot_dest_len) {
			goto no_use_compressing;
		    }
		    RETURN_STATE();
		case Z_STREAM_END:
		    {
			byte *dbytes = (byte *) context->s.cc.destination_bin->orig_bytes + 1;

			dbytes[0] = COMPRESSED;
			put_int32(context->s.cc.real_size-1,dbytes+1);
			erl_zlib_deflate_finish(&(context->s.cc.stream));
			result_bin = erts_bin_realloc(context->s.cc.destination_bin,
						      context->s.cc.dest_len+6);
			context->s.cc.destination_bin = NULL;
			pb = (ProcBin *) HAlloc(p, PROC_BIN_SIZE);
			pb->thing_word = HEADER_PROC_BIN;
			pb->size = context->s.cc.dest_len+6;
			pb->next = MSO(p).first;
			MSO(p).first = (struct erl_off_heap_header*)pb;
			pb->val = result_bin;
			pb->bytes = (byte*) result_bin->orig_bytes;
			pb->flags = 0;
			OH_OVERHEAD(&(MSO(p)), pb->size / sizeof(Eterm));
			erts_refc_inc(&result_bin->refc, 1);
			erts_bin_free(context->s.cc.result_bin);
			context->s.cc.result_bin = NULL;
			context->alive = 0;
			BUMP_REDS(p, (this_time * CONTEXT_REDS) / TERM_TO_BINARY_COMPRESS_CHUNK);
			if (context_b && erts_refc_read(&context_b->refc,0) == 0) {
			    erts_bin_free(context_b);
			}
			return make_binary(pb);
		    }
		default: /* Compression error, revert to uncompressed binary (still in 
			    context) */
		no_use_compressing:
		    result_bin = context->s.cc.result_bin;
		    context->s.cc.result_bin = NULL;
		    pb = (ProcBin *) HAlloc(p, PROC_BIN_SIZE);
		    pb->thing_word = HEADER_PROC_BIN;
		    pb->size = context->s.cc.real_size;
		    pb->next = MSO(p).first;
		    MSO(p).first = (struct erl_off_heap_header*)pb;
		    pb->val = result_bin;
		    pb->bytes = (byte*) result_bin->orig_bytes;
		    pb->flags = 0;
		    OH_OVERHEAD(&(MSO(p)), pb->size / sizeof(Eterm));
		    erts_refc_inc(&result_bin->refc, 1);
		    erl_zlib_deflate_finish(&(context->s.cc.stream));
		    erts_bin_free(context->s.cc.destination_bin);
		    context->s.cc.destination_bin = NULL;
		    context->alive = 0;
		    BUMP_REDS(p, (this_time * CONTEXT_REDS) / TERM_TO_BINARY_COMPRESS_CHUNK);
		    if (context_b && erts_refc_read(&context_b->refc,0) == 0) {
			erts_bin_free(context_b);
		    }
		    return make_binary(pb);
		}
	    }
	}
    }
#undef EXPORT_CONTEXT
#undef RETURN_STATE
}			








/*
 * This function fills ext with the external format of atom.
 * If it's an old atom we just supply an index, otherwise
 * we insert the index _and_ the entire atom. This way the receiving side
 * does not have to perform an hash on the etom to locate it, and
 * we save a lot of space on the wire.
 */

static byte*
enc_atom(ErtsAtomCacheMap *acmp, Eterm atom, byte *ep, Uint32 dflags)
{
    int iix;
    int len;
    int utf8_atoms = (int) (dflags & DFLAG_UTF8_ATOMS);

    ASSERT(is_atom(atom));

    if (dflags & DFLAG_INTERNAL_TAGS) {
	Uint aval = atom_val(atom);
	ASSERT(aval < (1<<24));
	if (aval >= (1 << 16)) {
	    *ep++ = ATOM_INTERNAL_REF3;
	    put_int24(aval, ep);
	    ep += 3;
	}
	else {
	    *ep++ = ATOM_INTERNAL_REF2;
	    put_int16(aval, ep);
	    ep += 2;
	}
	return ep;
    }

    /*
     * term_to_binary/1,2 and the initial distribution message
     * don't use the cache.
     */

    iix = get_iix_acache_map(acmp, atom, dflags);
    if (iix < 0) {
	Atom *a = atom_tab(atom_val(atom));
	len = a->len;
	if (utf8_atoms || a->latin1_chars < 0) {
	    if (len > 255) {
		*ep++ = ATOM_UTF8_EXT;
		put_int16(len, ep);
		ep += 2;
	    }
	    else {
		*ep++ = SMALL_ATOM_UTF8_EXT;
		put_int8(len, ep);
		ep += 1;
	    }
	    sys_memcpy((char *) ep, (char *) a->name, len);
	}
	else {
	    if (a->latin1_chars <= 255 && (dflags & DFLAG_SMALL_ATOM_TAGS)) {
		*ep++ = SMALL_ATOM_EXT;
		if (len == a->latin1_chars) {
		    sys_memcpy(ep+1, a->name, len);
		}
		else {
		    len = erts_utf8_to_latin1(ep+1, a->name, len);
		    ASSERT(len == a->latin1_chars);
		}
		put_int8(len, ep);
		ep++;
	    }
	    else {
		*ep++ = ATOM_EXT;
		if (len == a->latin1_chars) {
		    sys_memcpy(ep+2, a->name, len);
		}
		else {
		    len = erts_utf8_to_latin1(ep+2, a->name, len);
		    ASSERT(len == a->latin1_chars);
		}
		put_int16(len, ep);
		ep += 2;
	    }	    
	}
	ep += len;
	return ep;
    }

    /* The atom is referenced in the cache. */
    *ep++ = ATOM_CACHE_REF;
    put_int8(iix, ep);
    ep++;
    return ep;
}

/*
 * We use this atom as sysname in local pid/port/refs
 * for the ETS compressed format (DFLAG_INTERNAL_TAGS).
 *
 */
#define INTERNAL_LOCAL_SYSNAME am_ErtsSecretAtom

static byte*
enc_pid(ErtsAtomCacheMap *acmp, Eterm pid, byte* ep, Uint32 dflags)
{
    Uint on, os;
    Eterm sysname = ((is_internal_pid(pid) && (dflags & DFLAG_INTERNAL_TAGS))
		      ? INTERNAL_LOCAL_SYSNAME : pid_node_name(pid));
    Uint32 creation = pid_creation(pid);
    byte* tagp = ep++;

    /* insert  atom here containing host and sysname  */
    ep = enc_atom(acmp, sysname, ep, dflags);

    on = pid_number(pid);
    os = pid_serial(pid);

    put_int32(on, ep);
    ep += 4;
    put_int32(os, ep);
    ep += 4;
    if (creation <= ERTS_MAX_LOCAL_CREATION) {
        *tagp = PID_EXT;
        *ep++ = creation;
    } else {
        ASSERT(is_external_pid(pid));
        *tagp = NEW_PID_EXT;
        put_int32(creation, ep);
        ep += 4;
    }
    return ep;
}

/* Expect an atom in plain text or cached */
static byte*
dec_atom(ErtsDistExternal *edep, byte* ep, Eterm* objp)
{
    Uint len;
    int n;
    ErtsAtomEncoding char_enc;

    switch (*ep++) {
    case ATOM_CACHE_REF:
	if (!(edep && (edep->flags & ERTS_DIST_EXT_ATOM_TRANS_TAB)))
	    goto error;
	n = get_int8(ep);
	ep++;
	if (n >= edep->attab.size)
	    goto error;
	ASSERT(is_atom(edep->attab.atom[n]));
	*objp = edep->attab.atom[n];
	break;
    case ATOM_EXT:
	len = get_int16(ep),
	ep += 2;
	char_enc = ERTS_ATOM_ENC_LATIN1;
        goto dec_atom_common;
    case SMALL_ATOM_EXT:
	len = get_int8(ep);
	ep++;
	char_enc = ERTS_ATOM_ENC_LATIN1;
	goto dec_atom_common;
    case ATOM_UTF8_EXT:
	len = get_int16(ep),
	ep += 2;
	char_enc = ERTS_ATOM_ENC_UTF8;
	goto dec_atom_common;
    case SMALL_ATOM_UTF8_EXT:
	len = get_int8(ep),
	ep++;
	char_enc = ERTS_ATOM_ENC_UTF8;
    dec_atom_common:
        if (edep && (edep->flags & ERTS_DIST_EXT_BTT_SAFE)) {
	    if (!erts_atom_get((char*)ep, len, objp, char_enc)) {
                goto error;
	    }
        } else {
	    Eterm atom = erts_atom_put(ep, len, char_enc, 0);
	    if (is_non_value(atom))
		goto error;
            *objp = atom;
        }
	ep += len;
	break;
    case ATOM_INTERNAL_REF2:
	n = get_int16(ep);
	ep += 2;
	if (n >= atom_table_size()) {
	    goto error;
	}
	*objp = make_atom(n);
	break;
    case ATOM_INTERNAL_REF3:
	n = get_int24(ep);
	ep += 3;
	if (n >= atom_table_size()) {
	    goto error;
	}
	*objp = make_atom(n);
	break;

    default:
    error:
	*objp = NIL;	/* Don't leave a hole in the heap */
	return NULL;
    }
    return ep;
}

static ERTS_INLINE ErlNode* dec_get_node(Eterm sysname, Uint32 creation)
{
    if (sysname == INTERNAL_LOCAL_SYSNAME)  /* && DFLAG_INTERNAL_TAGS */
	return erts_this_node;

    if (sysname == erts_this_node->sysname
	&& (creation == erts_this_node->creation || creation == ORIG_CREATION))
	return erts_this_node;

    return erts_find_or_insert_node(sysname,creation);
}

static byte*
dec_pid(ErtsDistExternal *edep, ErtsHeapFactory* factory, byte* ep,
        Eterm* objp, byte tag)
{
    Eterm sysname;
    Uint data;
    Uint num;
    Uint ser;
    Uint32 cre;
    ErlNode *node;

    *objp = NIL;		/* In case we fail, don't leave a hole in the heap */

    /* eat first atom */
    if ((ep = dec_atom(edep, ep, &sysname)) == NULL)
	return NULL;
    num = get_int32(ep);
    ep += 4;
    if (num > ERTS_MAX_PID_NUMBER)
	return NULL;
    ser = get_int32(ep);
    ep += 4;
    if (ser > ERTS_MAX_PID_SERIAL)
	return NULL;

    if (tag == PID_EXT) {
        cre = get_int8(ep);
        ep += 1;
        if (!is_valid_creation(cre)) {
            return NULL;
        }
    } else {
        ASSERT(tag == NEW_PID_EXT);
        cre = get_int32(ep);
        ep += 4;
    }

    data = make_pid_data(ser, num);

    /*
     * We are careful to create the node entry only after all
     * validity tests are done.
     */
    node = dec_get_node(sysname, cre);

    if(node == erts_this_node) {
	*objp = make_internal_pid(data);
    } else {
	ExternalThing *etp = (ExternalThing *) factory->hp;
	factory->hp += EXTERNAL_THING_HEAD_SIZE + 1;

	etp->header = make_external_pid_header(1);
	etp->next = factory->off_heap->first;
	etp->node = node;
	etp->data.ui[0] = data;

	factory->off_heap->first = (struct erl_off_heap_header*) etp;
	*objp = make_external_pid(etp);
    }
    return ep;
}


#define ENC_TERM ((Eterm) 0)
#define ENC_ONE_CONS ((Eterm) 1)
#define ENC_PATCH_FUN_SIZE ((Eterm) 2)
#define ENC_BIN_COPY ((Eterm) 3)
#define ENC_MAP_PAIR ((Eterm) 4)
#define ENC_HASHMAP_NODE ((Eterm) 5)
#define ENC_LAST_ARRAY_ELEMENT ((Eterm) 6)

static byte*
enc_term(ErtsAtomCacheMap *acmp, Eterm obj, byte* ep, Uint32 dflags,
	 struct erl_off_heap_header** off_heap)
{
    byte *res;
    (void) enc_term_int(NULL, acmp, obj, ep, dflags, off_heap, NULL, &res);
    return res;
}

static int
enc_term_int(TTBEncodeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj, byte* ep, Uint32 dflags,
	     struct erl_off_heap_header** off_heap, Sint *reds, byte **res)
{
    DECLARE_WSTACK(s);
    Uint n;
    Uint i;
    Uint j;
    Uint* ptr;
    Eterm val;
    FloatDef f;
    Sint r = 0;

    if (ctx) {
	WSTACK_CHANGE_ALLOCATOR(s, ERTS_ALC_T_SAVED_ESTACK);
	r = *reds;

	if (ctx->wstack.wstart) { /* restore saved stacks and byte pointer */
	    WSTACK_RESTORE(s, &ctx->wstack);
	    ep = ctx->ep;
	    obj = ctx->obj;
	    if (is_non_value(obj)) {
		goto outer_loop;
	    }
	}
    }

    goto L_jump_start;

 outer_loop:
    while (!WSTACK_ISEMPTY(s)) {
	obj = WSTACK_POP(s);

	switch (val = WSTACK_POP(s)) {
	case ENC_TERM:
	    break;
	case ENC_ONE_CONS:
	encode_one_cons:
	    {
		Eterm* cons = list_val(obj);
		Eterm tl;

		obj = CAR(cons);
		tl = CDR(cons);
		WSTACK_PUSH2(s, (is_list(tl) ? ENC_ONE_CONS : ENC_TERM),
			     tl);
	    }
	    break;
	case ENC_PATCH_FUN_SIZE:
	    {
		byte* size_p = (byte *) obj;
		put_int32(ep - size_p, size_p);
	    }
	    goto outer_loop;
	case ENC_BIN_COPY: {
	    Uint bits = (Uint)obj;
	    Uint bitoffs = WSTACK_POP(s);
	    byte* bytes = (byte*) WSTACK_POP(s);
	    byte* dst = (byte*) WSTACK_POP(s);
	    if (bits > r * (TERM_TO_BINARY_MEMCPY_FACTOR * 8)) {
		Uint n = r * TERM_TO_BINARY_MEMCPY_FACTOR;
		WSTACK_PUSH5(s, (UWord)(dst + n), (UWord)(bytes + n), bitoffs,
			     ENC_BIN_COPY, bits - 8*n);
		bits = 8*n;
		copy_binary_to_buffer(dst, 0, bytes, bitoffs, bits);
		obj = THE_NON_VALUE;
		r = 0; /* yield */
		break;
	    } else {
		copy_binary_to_buffer(dst, 0, bytes, bitoffs, bits);
		r -= bits / (TERM_TO_BINARY_MEMCPY_FACTOR * 8);
		goto outer_loop;
	    }
	}
	case ENC_MAP_PAIR: {
	    Uint pairs_left = obj;
	    Eterm *vptr = (Eterm*) WSTACK_POP(s);
	    Eterm *kptr = (Eterm*) WSTACK_POP(s);

	    obj = *kptr;
	    if (--pairs_left > 0) {
		WSTACK_PUSH4(s, (UWord)(kptr+1), (UWord)(vptr+1),
			     ENC_MAP_PAIR, pairs_left);
	    }
	    WSTACK_PUSH2(s, ENC_TERM, *vptr);
	    break;
	}
	case ENC_HASHMAP_NODE:
	    if (is_list(obj)) { /* leaf node [K|V] */
		ptr = list_val(obj);
		WSTACK_PUSH2(s, ENC_TERM, CDR(ptr));
		obj = CAR(ptr);
	    }
	    break;
	case ENC_LAST_ARRAY_ELEMENT:
	    /* obj is the tuple */
	    {
		Eterm* ptr = (Eterm *) obj;
		obj = *ptr;
	    }
	    break;
	default:		/* ENC_LAST_ARRAY_ELEMENT+1 and upwards */
	    {
		Eterm* ptr = (Eterm *) obj;
		obj = *ptr++;
		WSTACK_PUSH2(s, val-1, (UWord)ptr);
	    }
	    break;
	}

    L_jump_start:

	if (ctx && --r <= 0) {
	    *reds = 0;
	    ctx->obj = obj;
	    ctx->ep = ep;
	    WSTACK_SAVE(s, &ctx->wstack);
	    return -1;
	}
	switch(tag_val_def(obj)) {
	case NIL_DEF:
	    *ep++ = NIL_EXT;
	    break;

	case ATOM_DEF:
	    ep = enc_atom(acmp,obj,ep,dflags);
	    break;

	case SMALL_DEF:
	    {
		/* From R14B we no longer restrict INTEGER_EXT to 28 bits,
		 * as done earlier for backward compatibility reasons. */
		Sint val = signed_val(obj);

		if ((Uint)val < 256) {
		    *ep++ = SMALL_INTEGER_EXT;
		    put_int8(val, ep);
		    ep++;
		} else if (sizeof(Sint) == 4 || IS_SSMALL32(val)) {
		    *ep++ = INTEGER_EXT;
		    put_int32(val, ep);
		    ep += 4;
		} else {
		    DeclareTmpHeapNoproc(tmp_big,2);
		    Eterm big;
		    UseTmpHeapNoproc(2);
		    big = small_to_big(val, tmp_big);
		    *ep++ = SMALL_BIG_EXT;
		    n = big_bytes(big);
		    ASSERT(n < 256);
		    put_int8(n, ep);
		    ep += 1;
		    *ep++ = big_sign(big);
		    ep = big_to_bytes(big, ep);
		    UnUseTmpHeapNoproc(2);
		}
	    }
	    break;

	case BIG_DEF:
	    {
		int sign = big_sign(obj);
		n = big_bytes(obj);
		if (sizeof(Sint)==4 && n<=4) {
		    Uint dig = big_digit(obj,0);		   
		    Sint val = sign ? -dig : dig;
		    if ((val<0) == sign) {
			*ep++ = INTEGER_EXT;
			put_int32(val, ep);
			ep += 4;
			break;
		    }
		}
		if (n < 256) {
		    *ep++ = SMALL_BIG_EXT;
		    put_int8(n, ep);
		    ep += 1;
		}
		else {
		    *ep++ = LARGE_BIG_EXT;
		    put_int32(n, ep);
		    ep += 4;
		}
		*ep++ = sign;
		ep = big_to_bytes(obj, ep);
	    }
	    break;

	case PID_DEF:
	case EXTERNAL_PID_DEF:
	    ep = enc_pid(acmp, obj, ep, dflags);
	    break;

	case REF_DEF:
	case EXTERNAL_REF_DEF: {
	    Uint32 *ref_num;
	    Eterm sysname = (((dflags & DFLAG_INTERNAL_TAGS) && is_internal_ref(obj))
			     ? INTERNAL_LOCAL_SYSNAME : ref_node_name(obj));
            Uint32 creation = ref_creation(obj);
            byte* tagp = ep++;

	    ASSERT(dflags & DFLAG_EXTENDED_REFERENCES);

	    erts_magic_ref_save_bin(obj);

	    i = ref_no_numbers(obj);
	    put_int16(i, ep);
	    ep += 2;
	    ep = enc_atom(acmp, sysname, ep, dflags);
            if (creation <= ERTS_MAX_LOCAL_CREATION) {
                *tagp = NEW_REFERENCE_EXT;
                *ep++ = creation;
            } else {
                ASSERT(is_external_ref(obj));
                *tagp = NEWER_REFERENCE_EXT;
                put_int32(creation, ep);
                ep += 4;
            }
	    ref_num = ref_numbers(obj);
	    for (j = 0; j < i; j++) {
		put_int32(ref_num[j], ep);
		ep += 4;
	    }
	    break;
	}
	case PORT_DEF:
	case EXTERNAL_PORT_DEF: {
	    Eterm sysname = (((dflags & DFLAG_INTERNAL_TAGS) && is_internal_port(obj))
			     ? INTERNAL_LOCAL_SYSNAME : port_node_name(obj));
            Uint32 creation = port_creation(obj);
            byte* tagp = ep++;

	    ep = enc_atom(acmp, sysname, ep, dflags);
	    j = port_number(obj);
	    put_int32(j, ep);
	    ep += 4;
            if (creation <= ERTS_MAX_LOCAL_CREATION) {
                *tagp = PORT_EXT;
                *ep++ = creation;
            } else {
                ASSERT(is_external_port(obj));
                *tagp = NEW_PORT_EXT;
                put_int32(creation, ep);
                ep += 4;
            }
	    break;
	}
	case LIST_DEF:
	    {
		int is_str;

		i = is_external_string(obj, &is_str);
		if (is_str) {
		    *ep++ = STRING_EXT;
		    put_int16(i, ep);
		    ep += 2;
		    while (is_list(obj)) {
			Eterm* cons = list_val(obj);
			*ep++ = unsigned_val(CAR(cons));
			obj = CDR(cons);
		    }
		} else {
		    *ep++ = LIST_EXT;
		    put_int32(i, ep);
		    ep += 4;
		    goto encode_one_cons;
		}
	    }
	    break;

	case TUPLE_DEF:
	    ptr = tuple_val(obj);
	    i = arityval(*ptr);
	    ptr++;
	    if (i <= 0xff) {
		*ep++ = SMALL_TUPLE_EXT;
		put_int8(i, ep);
		ep += 1;
	    } else  {
		*ep++ = LARGE_TUPLE_EXT;
		put_int32(i, ep);
		ep += 4;
	    }
	    if (i > 0) {
		WSTACK_PUSH2(s, ENC_LAST_ARRAY_ELEMENT+i-1, (UWord)ptr);
	    }
	    break;

	case MAP_DEF:
	    if (is_flatmap(obj)) {
		flatmap_t *mp = (flatmap_t*)flatmap_val(obj);
		Uint size = flatmap_get_size(mp);

		*ep++ = MAP_EXT;
		put_int32(size, ep); ep += 4;

		if (size > 0) {
		    Eterm *kptr = flatmap_get_keys(mp);
		    Eterm *vptr = flatmap_get_values(mp);

		    WSTACK_PUSH4(s, (UWord)kptr, (UWord)vptr,
				 ENC_MAP_PAIR, size);
		}
	    } else {
		Eterm hdr;
		Uint node_sz;
		ptr = boxed_val(obj);
		hdr = *ptr;
		ASSERT(is_header(hdr));
		switch(hdr & _HEADER_MAP_SUBTAG_MASK) {
		case HAMT_SUBTAG_HEAD_ARRAY:
		    *ep++ = MAP_EXT;
		    ptr++;
		    put_int32(*ptr, ep); ep += 4;
		    node_sz = 16;
		    break;
		case HAMT_SUBTAG_HEAD_BITMAP:
		    *ep++ = MAP_EXT;
		    ptr++;
		    put_int32(*ptr, ep); ep += 4;
		    /*fall through*/
		case HAMT_SUBTAG_NODE_BITMAP:
		    node_sz = hashmap_bitcount(MAP_HEADER_VAL(hdr));
		    ASSERT(node_sz < 17);
		    break;
		default:
		    erts_exit(ERTS_ERROR_EXIT, "bad header\r\n");
		}

		ptr++;
		WSTACK_RESERVE(s, node_sz*2);
		while(node_sz--) {
		    WSTACK_FAST_PUSH(s, ENC_HASHMAP_NODE);
		    WSTACK_FAST_PUSH(s, *ptr++);
		}
	    }
	    break;
	case FLOAT_DEF:
	    GET_DOUBLE(obj, f);
	    if (dflags & DFLAG_NEW_FLOATS) {
		*ep++ = NEW_FLOAT_EXT;
#if defined(WORDS_BIGENDIAN) || defined(DOUBLE_MIDDLE_ENDIAN)
		put_int32(f.fw[0], ep);
		ep += 4;
		put_int32(f.fw[1], ep);
#else
		put_int32(f.fw[1], ep);
		ep += 4;
		put_int32(f.fw[0], ep);
#endif		
		ep += 4;
	    } else {
		*ep++ = FLOAT_EXT;

		/* now the erts_snprintf which does the work */
		i = sys_double_to_chars(f.fd, (char*) ep, (size_t)31);

		/* Don't leave garbage after the float!  (Bad practice in general,
		 * and Purify complains.)
		 */
		sys_memset(ep+i, 0, 31-i);
		ep += 31;
	    }
	    break;

	case BINARY_DEF:
	    {
		Uint bitoffs;
		Uint bitsize;
		byte* bytes;
		byte* data_dst;

		ERTS_GET_BINARY_BYTES(obj, bytes, bitoffs, bitsize);
		if (dflags & DFLAG_INTERNAL_TAGS) {
		    ProcBin* pb = (ProcBin*) binary_val(obj);
		    Uint bytesize = pb->size;
		    if (pb->thing_word == HEADER_SUB_BIN) {
			ErlSubBin* sub = (ErlSubBin*)pb;
			pb = (ProcBin*) binary_val(sub->orig);
			ASSERT(bytesize == sub->size);
			bytesize += (bitoffs + bitsize + 7) / 8;
		    }
		    if (pb->thing_word == HEADER_PROC_BIN
			&& heap_bin_size(bytesize) > PROC_BIN_SIZE) {
			ProcBin tmp;
			if (bitoffs || bitsize) {
			    *ep++ = BIT_BINARY_INTERNAL_REF;
			    *ep++ = bitoffs;
			    *ep++ = bitsize;
			}
			else {
			    *ep++ = BINARY_INTERNAL_REF;
			}
			if (pb->flags) {
			    char* before_realloc = pb->val->orig_bytes; 
			    erts_emasculate_writable_binary(pb);
			    bytes += (pb->val->orig_bytes - before_realloc);
			}
			erts_refc_inc(&pb->val->refc, 2);

			sys_memcpy(&tmp, pb, sizeof(ProcBin));
			tmp.next = *off_heap;
			tmp.bytes = bytes;
			tmp.size = bytesize;
			sys_memcpy(ep, &tmp, sizeof(ProcBin));
			*off_heap = (struct erl_off_heap_header*) ep;
			ep += sizeof(ProcBin);
			break;
		    }
		}
		if (bitsize == 0) {
		    /* Plain old byte-sized binary. */
		    *ep++ = BINARY_EXT;
		    j = binary_size(obj);
		    put_int32(j, ep);
		    ep += 4;
		    data_dst = ep;
		    ep += j;
		} else if (dflags & DFLAG_BIT_BINARIES) {
		    /* Bit-level binary. */
		    *ep++ = BIT_BINARY_EXT;
		    j = binary_size(obj);
		    put_int32((j+1), ep);
		    ep += 4;
		    *ep++ = bitsize;
		    ep[j] = 0;	/* Zero unused bits at end of binary */
		    data_dst = ep;
		    ep += j + 1;
		} else {
		    /*
		     * Bit-level binary, but the receiver doesn't support it.
		     * Build a tuple instead.
		     */
		    *ep++ = SMALL_TUPLE_EXT;
		    *ep++ = 2;
		    *ep++ = BINARY_EXT;
		    j = binary_size(obj);
		    put_int32((j+1), ep);
		    ep += 4;
		    ep[j] = 0;	/* Zero unused bits at end of binary */
		    data_dst = ep;
		    ep += j+1;
		    *ep++ = SMALL_INTEGER_EXT;
		    *ep++ = bitsize;
		}
		if (ctx && j > r * TERM_TO_BINARY_MEMCPY_FACTOR) {
		    WSTACK_PUSH5(s, (UWord)data_dst, (UWord)bytes, bitoffs,
				 ENC_BIN_COPY, 8*j + bitsize);
		} else {
		    copy_binary_to_buffer(data_dst, 0, bytes, bitoffs,
					  8 * j + bitsize);
		}
	    }
	    break;
	case EXPORT_DEF:
	    {
		Export* exp = *((Export **) (export_val(obj) + 1));
		if ((dflags & DFLAG_EXPORT_PTR_TAG) != 0) {
		    *ep++ = EXPORT_EXT;
		    ep = enc_atom(acmp, exp->info.mfa.module, ep, dflags);
		    ep = enc_atom(acmp, exp->info.mfa.function, ep, dflags);
		    ep = enc_term(acmp, make_small(exp->info.mfa.arity),
                                  ep, dflags, off_heap);
		} else {
		    /* Tag, arity */
		    *ep++ = SMALL_TUPLE_EXT;
		    put_int8(2, ep);
		    ep += 1;

		    /* Module name */
		    ep = enc_atom(acmp, exp->info.mfa.module, ep, dflags);

		    /* Function name */
		    ep = enc_atom(acmp, exp->info.mfa.function, ep, dflags);
		}
		break;
	    }
	    break;
	case FUN_DEF:
	    {
		ErlFunThing* funp = (ErlFunThing *) fun_val(obj);
		int ei;

		if ((dflags & DFLAG_NEW_FUN_TAGS) != 0) {
		    *ep++ = NEW_FUN_EXT;
		    WSTACK_PUSH2(s, ENC_PATCH_FUN_SIZE,
				 (UWord) ep); /* Position for patching in size */
		    ep += 4;
		    *ep = funp->arity;
		    ep += 1;
		    sys_memcpy(ep, funp->fe->uniq, 16);
		    ep += 16;
		    put_int32(funp->fe->index, ep);
		    ep += 4;
		    put_int32(funp->num_free, ep);
		    ep += 4;
		    ep = enc_atom(acmp, funp->fe->module, ep, dflags);
		    ep = enc_term(acmp, make_small(funp->fe->old_index), ep, dflags, off_heap);
		    ep = enc_term(acmp, make_small(funp->fe->old_uniq), ep, dflags, off_heap);
		    ep = enc_pid(acmp, funp->creator, ep, dflags);
		} else {
		    /*
		     * Communicating with an obsolete erl_interface or
		     * jinterface node. Convert the fun to a tuple to
		     * avoid crasching.
		     */
		
		    /* Tag, arity */
		    *ep++ = SMALL_TUPLE_EXT;
		    put_int8(5, ep);
		    ep += 1;
		
		    /* 'fun' */
		    ep = enc_atom(acmp, am_fun, ep, dflags);
		
		    /* Module name */
		    ep = enc_atom(acmp, funp->fe->module, ep, dflags);
		
		    /* Index, Uniq */
		    *ep++ = INTEGER_EXT;
		    put_int32(funp->fe->old_index, ep);
		    ep += 4;
		    *ep++ = INTEGER_EXT;
		    put_int32(funp->fe->old_uniq, ep);
		    ep += 4;
		
		    /* Environment sub-tuple arity */
		    ASSERT(funp->num_free < MAX_ARG);
		    *ep++ = SMALL_TUPLE_EXT;
		    put_int8(funp->num_free, ep);
		    ep += 1;
		}
		for (ei = funp->num_free-1; ei > 0; ei--) {
		    WSTACK_PUSH2(s, ENC_TERM, (UWord) funp->env[ei]);
		}
		if (funp->num_free != 0) {
		    obj = funp->env[0];
		    goto L_jump_start;
		}
	    }
	    break;
	}
    }
    DESTROY_WSTACK(s);
    if (ctx) {
	ASSERT(ctx->wstack.wstart == NULL);
	*reds = r;
    }
    *res = ep;
    return 0;
}

static
Uint
is_external_string(Eterm list, int* p_is_string)
{
    Uint len = 0;

    /*
     * Calculate the length of the list as long as all characters
     * are integers from 0 through 255.
     */
    while (is_list(list)) {
	Eterm* consp = list_val(list);
	Eterm hd = CAR(consp);

	if (!is_byte(hd)) {
	    break;
	}
	len++;
	list = CDR(consp);
    }

    /*
     * If we have reached the end of the list, and we have
     * not exceeded the maximum length of a string, this
     * is a string.
     */
    *p_is_string = is_nil(list) && len < MAX_STRING_LEN;

    /*
     * Continue to calculate the length.
     */
    while (is_list(list)) {
	Eterm* consp = list_val(list);
	len++;
	list = CDR(consp);
    }
    return len;
}


struct dec_term_hamt
{
    Eterm* objp; /* write result here */
    Uint size;   /* nr of leafs */
    Eterm* leaf_array;
};


/* Decode term from external format into *objp.
** On failure calls erts_factory_undo() and returns NULL
*/
static byte*
dec_term(ErtsDistExternal *edep,
	 ErtsHeapFactory* factory,
	 byte* ep,
         Eterm* objp,
	 B2TContext* ctx)
{
#define PSTACK_TYPE struct dec_term_hamt
    PSTACK_DECLARE(hamt_array, 5);
    int n;
    ErtsAtomEncoding char_enc;
    register Eterm* hp;        /* Please don't take the address of hp */
    DECLARE_WSTACK(flat_maps); /* for preprocessing of small maps */
    Eterm* next;
    SWord reds;
#ifdef DEBUG
    Eterm* dbg_resultp = ctx ? &ctx->u.dc.res : objp;
#endif

    if (ctx) {
        reds     = ctx->reds;
        next     = ctx->u.dc.next;
        ep       = ctx->u.dc.ep;
	factory  = &ctx->u.dc.factory;

        if (ctx->state != B2TDecode) {
            int n_limit = reds;

	    n = ctx->u.dc.remaining_n;
            if (ctx->state == B2TDecodeBinary) {
                n_limit *= B2T_MEMCPY_FACTOR;
                ASSERT(n_limit >= reds);
		reds -= n / B2T_MEMCPY_FACTOR;
            }
	    else
		reds -= n;

            if (n > n_limit) {
                ctx->u.dc.remaining_n -= n_limit;
                n = n_limit;
                reds = 0;
            }
            else {
                ctx->u.dc.remaining_n = 0;
            }

            switch (ctx->state) {
            case B2TDecodeList:
                objp = next - 2;
                while (n > 0) {
                    objp[0] = (Eterm) next;
                    objp[1] = make_list(next);
                    next = objp;
                    objp -= 2;
                    n--;
                }
                break;

            case B2TDecodeTuple:
                objp = next - 1;
                while (n-- > 0) {
                    objp[0] = (Eterm) next;
                    next = objp;
                    objp--;
                }
                break;

            case B2TDecodeString:
                hp = factory->hp;
                hp[-1] = make_list(hp);  /* overwrite the premature NIL */
                while (n-- > 0) {
                    hp[0] = make_small(*ep++);
                    hp[1] = make_list(hp+2);
                    hp += 2;
                }
                hp[-1] = NIL;
		factory->hp = hp;
                break;

            case B2TDecodeBinary:
                sys_memcpy(ctx->u.dc.remaining_bytes, ep, n);
                ctx->u.dc.remaining_bytes += n;
                ep += n;
                break;

            default:
                ASSERT(!"Unknown state");
            }
            if (!ctx->u.dc.remaining_n) {
                ctx->state = B2TDecode;
            }
            if (reds <= 0) {
                ctx->u.dc.next = next;
                ctx->u.dc.ep = ep;
                ctx->reds = 0;
                return NULL;
            }
        }
	PSTACK_CHANGE_ALLOCATOR(hamt_array, ERTS_ALC_T_SAVED_ESTACK);
        WSTACK_CHANGE_ALLOCATOR(flat_maps, ERTS_ALC_T_SAVED_ESTACK);
	if (ctx->u.dc.hamt_array.pstart) {
	    PSTACK_RESTORE(hamt_array, &ctx->u.dc.hamt_array);
	}
	if (ctx->u.dc.flat_maps.wstart) {
	    WSTACK_RESTORE(flat_maps, &ctx->u.dc.flat_maps);
	}
    }
    else {
        reds = ERTS_SWORD_MAX;
        next = objp;
        *next = (Eterm) (UWord) NULL;
    }
    hp = factory->hp;

    while (next != NULL) {

	objp = next;
	next = (Eterm *) *objp;

	switch (*ep++) {
	case INTEGER_EXT:
	    {
		Sint sn = get_int32(ep);

		ep += 4;
#if defined(ARCH_64)
		*objp = make_small(sn);
#else
		if (MY_IS_SSMALL(sn)) {
		    *objp = make_small(sn);
		} else {
		    *objp = small_to_big(sn, hp);
		    hp += BIG_UINT_HEAP_SIZE;
		}
#endif
		break;
	    }
	case SMALL_INTEGER_EXT:
	    n = get_int8(ep);
	    ep++;
	    *objp = make_small(n);
	    break;
	case SMALL_BIG_EXT:
	    n = get_int8(ep);
	    ep++;
	    goto big_loop;
	case LARGE_BIG_EXT:
	    n = get_int32(ep);
	    ep += 4;
	big_loop:
	    {
		Eterm big;
		byte* first;
		byte* last;
		Uint neg;

		neg = get_int8(ep); /* Sign bit */
		ep++;

		/*
		 * Strip away leading zeroes to avoid creating illegal bignums.
		 */
		first = ep;
		last = ep + n;
		ep += n;
		do {
		    --last;
		} while (first <= last && *last == 0);

		if ((n = last - first + 1) == 0) {
		    /* Zero width bignum defaults to zero */
		    big = make_small(0);
		} else {
		    big = bytes_to_big(first, n, neg, hp);
		    if (is_nil(big))
			goto error;
		    if (is_big(big)) {
			hp += big_arity(big) + 1;
		    }
		}
		*objp = big;
		break;
	    }
	case ATOM_CACHE_REF:
	    if (edep == 0 || (edep->flags & ERTS_DIST_EXT_ATOM_TRANS_TAB) == 0) {
		goto error;
	    }
	    n = get_int8(ep);
	    ep++;
	    if (n >= edep->attab.size)
		goto error;
	    ASSERT(is_atom(edep->attab.atom[n]));
	    *objp = edep->attab.atom[n];
	    break;
	case ATOM_EXT:
	    n = get_int16(ep);
	    ep += 2;
	    char_enc = ERTS_ATOM_ENC_LATIN1;
	    goto dec_term_atom_common;
	case SMALL_ATOM_EXT:
	    n = get_int8(ep);
	    ep++;
	    char_enc = ERTS_ATOM_ENC_LATIN1;
	    goto dec_term_atom_common;
	case ATOM_UTF8_EXT:
	    n = get_int16(ep);
	    ep += 2;
	    char_enc = ERTS_ATOM_ENC_UTF8;
	    goto dec_term_atom_common;
	case SMALL_ATOM_UTF8_EXT:
	    n = get_int8(ep);
	    ep++;
	    char_enc = ERTS_ATOM_ENC_UTF8;
dec_term_atom_common:
	    if (edep && (edep->flags & ERTS_DIST_EXT_BTT_SAFE)) {
		if (!erts_atom_get((char*)ep, n, objp, char_enc)) {
		    goto error;
		}
	    } else {
		Eterm atom = erts_atom_put(ep, n, char_enc, 0);
		if (is_non_value(atom))
		    goto error;
	        *objp = atom;
	    }
	    ep += n;
	    break;
	case LARGE_TUPLE_EXT:
	    n = get_int32(ep);
	    ep += 4;
	    goto tuple_loop;
	case SMALL_TUPLE_EXT:
	    n = get_int8(ep);
	    ep++;
	tuple_loop:
	    *objp = make_tuple(hp);
	    *hp++ = make_arityval(n);
	    hp += n;
            objp = hp - 1;
            if (ctx) {
                if (reds < n) {
                    ASSERT(reds > 0);
                    ctx->state = B2TDecodeTuple;
                    ctx->u.dc.remaining_n = n - reds;
                    n = reds;
                }
		reds -= n;
	    }
	    while (n-- > 0) {
		objp[0] = (Eterm) next;
		next = objp;
		objp--;
	    }
	    break;
	case NIL_EXT:
	    *objp = NIL;
	    break;
	case LIST_EXT:
	    n = get_int32(ep);
	    ep += 4;
	    if (n == 0) {
		next = objp;
		break;
	    }
	    *objp = make_list(hp);
            hp += 2 * n;
	    objp = hp - 2;
	    objp[0] = (Eterm) (objp+1);
	    objp[1] = (Eterm) next;
	    next = objp;
	    objp -= 2;
            n--;
	    if (ctx) {
                if (reds < n) {
		    ctx->state = B2TDecodeList;
		    ctx->u.dc.remaining_n = n - reds;
		    n = reds;
		}
		reds -= n;
	    }
            while (n > 0) {
		objp[0] = (Eterm) next;
		objp[1] = make_list(next);
		next = objp;
		objp -= 2;
                n--;
	    }
	    break;
	case STRING_EXT:
	    n = get_int16(ep);
	    ep += 2;
	    if (n == 0) {
		*objp = NIL;
		break;
	    }
	    *objp = make_list(hp);
            if (ctx) {
                if (reds < n) {
                    ctx->state = B2TDecodeString;
                    ctx->u.dc.remaining_n = n - reds;
                    n = reds;
		}
                reds -= n;
            }
	    while (n-- > 0) {
		hp[0] = make_small(*ep++);
		hp[1] = make_list(hp+2);
		hp += 2;
	    }
	    hp[-1] = NIL;
	    break;
	case FLOAT_EXT:
	    {
		FloatDef ff;

		if (sys_chars_to_double((char*)ep, &ff.fd) != 0) {
		    goto error;
		}
		ep += 31;
		*objp = make_float(hp);
		PUT_DOUBLE(ff, hp);
		hp += FLOAT_SIZE_OBJECT;
		break;
	    }
	case NEW_FLOAT_EXT:
	    {
		FloatDef ff;
#ifndef NO_FPE_SIGNALS
		volatile unsigned long *fpexnp = erts_get_current_fp_exception();
#endif

#if defined(WORDS_BIGENDIAN) || defined(DOUBLE_MIDDLE_ENDIAN)
		ff.fw[0] = get_int32(ep);
		ep += 4;
		ff.fw[1] = get_int32(ep);
		ep += 4;
#else
		ff.fw[1] = get_int32(ep);
		ep += 4;
		ff.fw[0] = get_int32(ep);
		ep += 4;
#endif		
		__ERTS_FP_CHECK_INIT(fpexnp);
		__ERTS_FP_ERROR_THOROUGH(fpexnp, ff.fd, goto error);
		*objp = make_float(hp);
		PUT_DOUBLE(ff, hp);
		hp += FLOAT_SIZE_OBJECT;
		break;
	    }
        case PID_EXT:
        case NEW_PID_EXT:
	    factory->hp = hp;
	    ep = dec_pid(edep, factory, ep, objp, ep[-1]);
	    hp = factory->hp;
	    if (ep == NULL) {
		goto error;
	    }
	    break;
        case PORT_EXT:
        case NEW_PORT_EXT:
	    {
		Eterm sysname;
		ErlNode *node;
		Uint num;
		Uint32 cre;
                byte tag = ep[-1];

		if ((ep = dec_atom(edep, ep, &sysname)) == NULL) {
		    goto error;
		}
		if ((num = get_int32(ep)) > ERTS_MAX_PORT_NUMBER) {
		    goto error;
		}
		ep += 4;
                if (tag == PORT_EXT) {
                    cre = get_int8(ep);
                    ep++;
                    if (!is_valid_creation(cre)) {
                        goto error;
                    }
                }
                else {
                    cre = get_int32(ep);
                    ep += 4;
                }
		node = dec_get_node(sysname, cre);
		if(node == erts_this_node) {
		    *objp = make_internal_port(num);
		}
		else {
		    ExternalThing *etp = (ExternalThing *) hp;
		    hp += EXTERNAL_THING_HEAD_SIZE + 1;
		    
		    etp->header = make_external_port_header(1);
		    etp->next = factory->off_heap->first;
		    etp->node = node;
		    etp->data.ui[0] = num;

		    factory->off_heap->first = (struct erl_off_heap_header*)etp;
		    *objp = make_external_port(etp);
		}

		break;
	    }
	case REFERENCE_EXT:
	    {
		Eterm sysname;
		ErlNode *node;
		int i;
		Uint32 cre;
		Uint32 *ref_num;
		Uint32 r0;
		Uint ref_words;

		ref_words = 1;

		if ((ep = dec_atom(edep, ep, &sysname)) == NULL)
		    goto error;
		if ((r0 = get_int32(ep)) >= MAX_REFERENCE )
		    goto error;
		ep += 4;

		cre = get_int8(ep);
		ep += 1;
		if (!is_valid_creation(cre)) {
		    goto error;
		}
		goto ref_ext_common;

	    case NEW_REFERENCE_EXT:
		ref_words = get_int16(ep);
		ep += 2;

		if ((ep = dec_atom(edep, ep, &sysname)) == NULL)
		    goto error;

		cre = get_int8(ep);
		ep += 1;
		if (!is_valid_creation(cre)) {
		    goto error;
		}
		r0 = get_int32(ep);
		ep += 4;
		if (r0 >= MAX_REFERENCE)
		    goto error;
		goto ref_ext_common;

            case NEWER_REFERENCE_EXT:
		ref_words = get_int16(ep);
		ep += 2;

		if ((ep = dec_atom(edep, ep, &sysname)) == NULL)
		    goto error;

		cre = get_int32(ep);
		ep += 4;
		r0 = get_int32(ep); /* allow full word */
		ep += 4;

	    ref_ext_common: {
		ErtsORefThing *rtp;

		if (ref_words > ERTS_MAX_REF_NUMBERS)
		    goto error;

		node = dec_get_node(sysname, cre);
		if(node == erts_this_node) {
	
		    rtp = (ErtsORefThing *) hp;
		    ref_num = &rtp->num[0];
		    if (ref_words != ERTS_REF_NUMBERS) {
                        int i;
                        if (ref_words > ERTS_REF_NUMBERS)
                            goto error; /* Not a ref that we created... */
                        for (i = ref_words; i < ERTS_REF_NUMBERS; i++)
                            ref_num[i] = 0;
		    }

#ifdef ERTS_ORDINARY_REF_MARKER
		    rtp->marker = ERTS_ORDINARY_REF_MARKER;
#endif
		    hp += ERTS_REF_THING_SIZE;
		    rtp->header = ERTS_REF_THING_HEADER;
		    *objp = make_internal_ref(rtp);
		}
		else {
		    ExternalThing *etp = (ExternalThing *) hp;
		    rtp = NULL;
#if defined(ARCH_64)
		    hp += EXTERNAL_THING_HEAD_SIZE + ref_words/2 + 1;
#else
		    hp += EXTERNAL_THING_HEAD_SIZE + ref_words;
#endif

#if defined(ARCH_64)
		    etp->header = make_external_ref_header(ref_words/2 + 1);
#else
		    etp->header = make_external_ref_header(ref_words);
#endif
		    etp->next = factory->off_heap->first;
		    etp->node = node;

		    factory->off_heap->first = (struct erl_off_heap_header*)etp;
		    *objp = make_external_ref(etp);
		    ref_num = &(etp->data.ui32[0]);
#if defined(ARCH_64)
		    *(ref_num++) = ref_words /* 32-bit arity */;
#endif
		}

		ref_num[0] = r0;

		for(i = 1; i < ref_words; i++) {
		    ref_num[i] = get_int32(ep);
		    ep += 4;
		}
#if defined(ARCH_64)
		if ((1 + ref_words) % 2)
		    ref_num[ref_words] = 0;
#endif
		if (node == erts_this_node) {
		    /* Check if it was a magic reference... */
		    ErtsMagicBinary *mb = erts_magic_ref_lookup_bin(ref_num);
		    if (mb) {
			/*
			 * Was a magic ref; adjust it...
			 *
			 * Refc on binary was increased by lookup above...
			 */
			ASSERT(rtp);
			hp = (Eterm *) rtp;
			write_magic_ref_thing(hp, factory->off_heap, mb);
                        OH_OVERHEAD(factory->off_heap,
                                    mb->orig_size / sizeof(Eterm));
			hp += ERTS_MAGIC_REF_THING_SIZE;
		    }
		}
		break;
	    }
	    }
	case BINARY_EXT:
	    {
		n = get_int32(ep);
		ep += 4;
	    
		if ((unsigned)n <= ERL_ONHEAP_BIN_LIMIT) {
		    ErlHeapBin* hb = (ErlHeapBin *) hp;

		    hb->thing_word = header_heap_bin(n);
		    hb->size = n;
		    hp += heap_bin_size(n);
		    sys_memcpy(hb->data, ep, n);
		    *objp = make_binary(hb);
		} else {
		    Binary* dbin = erts_bin_nrml_alloc(n);
		    ProcBin* pb;
		    erts_refc_init(&dbin->refc, 1);
		    pb = (ProcBin *) hp;
		    hp += PROC_BIN_SIZE;
		    pb->thing_word = HEADER_PROC_BIN;
		    pb->size = n;
		    pb->next = factory->off_heap->first;
		    factory->off_heap->first = (struct erl_off_heap_header*)pb;
		    OH_OVERHEAD(factory->off_heap, pb->size / sizeof(Eterm));
		    pb->val = dbin;
		    pb->bytes = (byte*) dbin->orig_bytes;
		    pb->flags = 0;
		    *objp = make_binary(pb);
                    if (ctx) {
                        int n_limit = reds * B2T_MEMCPY_FACTOR;
                        if (n > n_limit) {
                            ctx->state = B2TDecodeBinary;
                            ctx->u.dc.remaining_n = n - n_limit;
                            ctx->u.dc.remaining_bytes = dbin->orig_bytes + n_limit;
                            n = n_limit;
                            reds = 0;
                        }
                        else
                            reds -= n / B2T_MEMCPY_FACTOR;
                    }
                    sys_memcpy(dbin->orig_bytes, ep, n);
                }
		ep += n;
		break;
	    }
	case BIT_BINARY_EXT:
	    {
		Eterm bin;
		ErlSubBin* sb;
		Uint bitsize;

		n = get_int32(ep);
		bitsize = ep[4];
                if (((bitsize==0) != (n==0)) || bitsize > 8)
                    goto error;
                ep += 5;
		if ((unsigned)n <= ERL_ONHEAP_BIN_LIMIT) {
		    ErlHeapBin* hb = (ErlHeapBin *) hp;

		    hb->thing_word = header_heap_bin(n);
		    hb->size = n;
		    sys_memcpy(hb->data, ep, n);
		    bin = make_binary(hb);
		    hp += heap_bin_size(n);
                    ep += n;
		} else {
		    Binary* dbin = erts_bin_nrml_alloc(n);
		    ProcBin* pb;

		    erts_refc_init(&dbin->refc, 1);
		    pb = (ProcBin *) hp;
		    pb->thing_word = HEADER_PROC_BIN;
		    pb->size = n;
		    pb->next = factory->off_heap->first;
		    factory->off_heap->first = (struct erl_off_heap_header*)pb;
		    OH_OVERHEAD(factory->off_heap, pb->size / sizeof(Eterm));
		    pb->val = dbin;
		    pb->bytes = (byte*) dbin->orig_bytes;
		    pb->flags = 0;
		    bin = make_binary(pb);
		    hp += PROC_BIN_SIZE;
                    if (ctx) {
                        int n_limit = reds * B2T_MEMCPY_FACTOR;
                        if (n > n_limit) {
                            ctx->state = B2TDecodeBinary;
                            ctx->u.dc.remaining_n = n - n_limit;
                            ctx->u.dc.remaining_bytes = dbin->orig_bytes + n_limit;
                            n = n_limit;
                            reds = 0;
                        }
                        else
                            reds -= n / B2T_MEMCPY_FACTOR;
                    }
                    sys_memcpy(dbin->orig_bytes, ep, n);
                    ep += n;
                    n = pb->size;
                }

		if (bitsize == 8 || n == 0) {
		    *objp = bin;
		} else {
                    sb = (ErlSubBin *)hp;
		    sb->thing_word = HEADER_SUB_BIN;
		    sb->orig = bin;
		    sb->size = n - 1;
		    sb->bitsize = bitsize;
		    sb->bitoffs = 0;
		    sb->offs = 0;
		    sb->is_writable = 0;
		    *objp = make_binary(sb);
		    hp += ERL_SUB_BIN_SIZE;
		}
		break;
	    }
	case EXPORT_EXT:
	    {
		Eterm mod;
		Eterm name;
		Eterm temp;
		Sint arity;

		if ((ep = dec_atom(edep, ep, &mod)) == NULL) {
		    goto error;
		}
		if ((ep = dec_atom(edep, ep, &name)) == NULL) {
		    goto error;
		}
		factory->hp = hp;
		ep = dec_term(edep, factory, ep, &temp, NULL);
		hp = factory->hp;
		if (ep == NULL) {
		    goto error;
		}
		if (!is_small(temp)) {
		    goto error;
		}
		arity = signed_val(temp);
		if (arity < 0) {
		    goto error;
		}
		if (edep && (edep->flags & ERTS_DIST_EXT_BTT_SAFE)) {
		    if (!erts_active_export_entry(mod, name, arity))
			goto error;
                }
		*objp = make_export(hp);
		*hp++ = HEADER_EXPORT;
		*hp++ = (Eterm) erts_export_get_or_make_stub(mod, name, arity);
		break;
	    }
	    break;
	case MAP_EXT:
	    {
		Uint32 size,n;
		Eterm *kptr,*vptr;
		Eterm keys;

		size = get_int32(ep); ep += 4;

                if (size <= MAP_SMALL_MAP_LIMIT) {
                    flatmap_t *mp;

                    keys  = make_tuple(hp);
                    *hp++ = make_arityval(size);
                    hp   += size;
                    kptr = hp - 1;

                    mp    = (flatmap_t*)hp;
                    hp   += MAP_HEADER_FLATMAP_SZ;
                    hp   += size;
                    vptr = hp - 1;

                    /* kptr, last word for keys
                     * vptr, last word for values
                     */

                    WSTACK_PUSH(flat_maps, (UWord)mp);
                    mp->thing_word = MAP_HEADER_FLATMAP;
                    mp->size       = size;
                    mp->keys       = keys;
                    *objp          = make_flatmap(mp);

                    for (n = size; n; n--) {
                        *vptr = (Eterm) next;
                        *kptr = (Eterm) vptr;
                        next  = kptr;
                        vptr--;
                        kptr--;
                    }
                }
                else {  /* Make hamt */
                    struct dec_term_hamt* hamt = PSTACK_PUSH(hamt_array);

                    hamt->objp = objp;
                    hamt->size = size;
                    hamt->leaf_array = hp;

                    for (n = size; n; n--) {
                        CDR(hp) = (Eterm) next;
                        CAR(hp) = (Eterm) &CDR(hp);
                        next = &CAR(hp);
                        hp += 2;
                    }
                }
	    }
	    break;
	case NEW_FUN_EXT:
	    {
		ErlFunThing* funp = (ErlFunThing *) hp;
		Uint arity;
		Eterm module;
		byte* uniq;
		int index;
		Sint old_uniq;
		Sint old_index;
		unsigned num_free;
		int i;
		Eterm temp;

		ep += 4;	/* Skip total size in bytes */
		arity = *ep++;
		uniq = ep;
		ep += 16;
		index = get_int32(ep);
		ep += 4;
		num_free = get_int32(ep);
		ep += 4;
		hp += ERL_FUN_SIZE;
		hp += num_free;
		funp->thing_word = HEADER_FUN;
		funp->num_free = num_free;
		*objp = make_fun(funp);

		/* Module */
		if ((ep = dec_atom(edep, ep, &module)) == NULL) {
		    goto error;
		}
		factory->hp = hp;
		/* Index */
		if ((ep = dec_term(edep, factory, ep, &temp, NULL)) == NULL) {
		    goto error;
		}
		if (!is_small(temp)) {
		    goto error;
		}
		old_index = unsigned_val(temp);

		/* Uniq */
		if ((ep = dec_term(edep, factory, ep, &temp, NULL)) == NULL) {
		    goto error;
		}
		if (!is_small(temp)) {
		    goto error;
		}
		old_uniq = unsigned_val(temp);

		/*
		 * It is safe to link the fun into the fun list only when
		 * no more validity tests can fail.
		 */
		funp->next = factory->off_heap->first;
		factory->off_heap->first = (struct erl_off_heap_header*)funp;

		funp->fe = erts_put_fun_entry2(module, old_uniq, old_index,
					       uniq, index, arity);
		funp->arity = arity;
#ifdef HIPE
		if (funp->fe->native_address == NULL) {
		    hipe_set_closure_stub(funp->fe);
		}
#endif
		hp = factory->hp;

		/* Environment */
		for (i = num_free-1; i >= 0; i--) {
		    funp->env[i] = (Eterm) next;
		    next = funp->env + i;
		}
		/* Creator */
		funp->creator = (Eterm) next;
		next = &(funp->creator);
		break;
	    }
	case FUN_EXT:
	    {
		ErlFunThing* funp = (ErlFunThing *) hp;
		Eterm module;
		Sint old_uniq;
		Sint old_index;
		unsigned num_free;
		int i;
		Eterm temp;

		num_free = get_int32(ep);
		ep += 4;
		hp += ERL_FUN_SIZE;
		hp += num_free;
		factory->hp = hp;
		funp->thing_word = HEADER_FUN;
		funp->num_free = num_free;
		*objp = make_fun(funp);

		/* Creator pid */
		if ((*ep != PID_EXT && *ep != NEW_PID_EXT)
		    || (ep = dec_pid(edep, factory, ep+1,
				     &funp->creator, *ep))==NULL) {
		    goto error;
		}

		/* Module */
		if ((ep = dec_atom(edep, ep, &module)) == NULL) {
		    goto error;
		}

		/* Index */
		if ((ep = dec_term(edep, factory, ep, &temp, NULL)) == NULL) {
		    goto error;
		}
		if (!is_small(temp)) {
		    goto error;
		}
		old_index = unsigned_val(temp);

		/* Uniq */
		if ((ep = dec_term(edep, factory, ep, &temp, NULL)) == NULL) {
		    goto error;
		}
		if (!is_small(temp)) {
		    goto error;
		}
		
		/*
		 * It is safe to link the fun into the fun list only when
		 * no more validity tests can fail.
		 */
		funp->next = factory->off_heap->first;
		factory->off_heap->first = (struct erl_off_heap_header*)funp;
		old_uniq = unsigned_val(temp);

		funp->fe = erts_put_fun_entry(module, old_uniq, old_index);
		funp->arity = funp->fe->address[-1] - num_free;
		hp = factory->hp;

		/* Environment */
		for (i = num_free-1; i >= 0; i--) {
		    funp->env[i] = (Eterm) next;
		    next = funp->env + i;
		}
		break;
	    }
	case ATOM_INTERNAL_REF2:
	    n = get_int16(ep);
	    ep += 2;
	    if (n >= atom_table_size()) {
		goto error;
	    }
	    *objp = make_atom(n);
	    break;
	case ATOM_INTERNAL_REF3:
	    n = get_int24(ep);
	    ep += 3;
	    if (n >= atom_table_size()) {
		goto error;
	    }
	    *objp = make_atom(n);
	    break;

	case BINARY_INTERNAL_REF:
	    {
		ProcBin* pb = (ProcBin*) hp;
		sys_memcpy(pb, ep, sizeof(ProcBin));
		ep += sizeof(ProcBin);

		erts_refc_inc(&pb->val->refc, 1);
		hp += PROC_BIN_SIZE;
		pb->next = factory->off_heap->first;
		factory->off_heap->first = (struct erl_off_heap_header*)pb;
		OH_OVERHEAD(factory->off_heap, pb->size / sizeof(Eterm));
		pb->flags = 0;
		*objp = make_binary(pb);
		break;
	    }
	case BIT_BINARY_INTERNAL_REF:
	    {
		Sint bitoffs = *ep++;
		Sint bitsize = *ep++;
		ProcBin* pb = (ProcBin*) hp;
		ErlSubBin* sub;
		sys_memcpy(pb, ep, sizeof(ProcBin));
		ep += sizeof(ProcBin);

		erts_refc_inc(&pb->val->refc, 1);
		hp += PROC_BIN_SIZE;
		pb->next = factory->off_heap->first;
		factory->off_heap->first = (struct erl_off_heap_header*)pb;
                OH_OVERHEAD(factory->off_heap, pb->size / sizeof(Eterm));
		pb->flags = 0;

		sub = (ErlSubBin*)hp;
		sub->thing_word = HEADER_SUB_BIN;
		sub->size = pb->size - (bitoffs + bitsize + 7)/8;
		sub->offs = 0;
		sub->bitoffs = bitoffs;
		sub->bitsize = bitsize;
		sub->is_writable = 0;
		sub->orig = make_binary(pb);

		hp += ERL_SUB_BIN_SIZE;
		*objp = make_binary(sub);
		break;
	    }

	default:
	    goto error;
	}

        if (--reds <= 0) {
            if (ctx) {
                if (next || ctx->state != B2TDecode) {
                    ctx->u.dc.ep = ep;
                    ctx->u.dc.next = next;
                    ctx->u.dc.factory.hp = hp;
		    if (!WSTACK_ISEMPTY(flat_maps)) {
			WSTACK_SAVE(flat_maps, &ctx->u.dc.flat_maps);
		    }
		    if (!PSTACK_IS_EMPTY(hamt_array)) {
			PSTACK_SAVE(hamt_array, &ctx->u.dc.hamt_array);
		    }
                    ctx->reds = 0;
                    return NULL;
                }
            }
            else {
                reds = ERTS_SWORD_MAX;
            }
        }
    }

    ASSERT(hp <= factory->hp_end
           || (factory->mode == FACTORY_CLOSED && is_immed(*dbg_resultp)));
    factory->hp = hp;
    /*
     * From here on factory may produce (more) heap fragments
     */

    if (!PSTACK_IS_EMPTY(hamt_array)) {
        do {
            struct dec_term_hamt* hamt = PSTACK_TOP(hamt_array);

            *hamt->objp = erts_hashmap_from_array(factory,
                                                  hamt->leaf_array,
                                                  hamt->size,
                                                  1);
            if (is_non_value(*hamt->objp))
                goto error_hamt;

            (void) PSTACK_POP(hamt_array);
        } while (!PSTACK_IS_EMPTY(hamt_array));
        PSTACK_DESTROY(hamt_array);
    }

    /* Iterate through all the (flat)maps and check for validity and sort keys
     * - done here for when we know it is complete.
     */

    while(!WSTACK_ISEMPTY(flat_maps)) {
        next = (Eterm *)WSTACK_POP(flat_maps);
        if (!erts_validate_and_sort_flatmap((flatmap_t*)next))
            goto error;
    }
    WSTACK_DESTROY(flat_maps);

    ASSERT((Eterm*)*dbg_resultp != NULL);

    if (ctx) {
        ctx->state = B2TDone;
	ctx->reds = reds;
    }

    return ep;

error:
    /* UNDO:
     * Must unlink all off-heap objects that may have been
     * linked into the process. 
     */
    if (factory->mode != FACTORY_CLOSED) {
	if (factory->hp < hp) { /* Sometimes we used hp and sometimes factory->hp */
	    factory->hp = hp;   /* the largest must be the freshest */
	}
    }
    else ASSERT(factory->hp == hp);

error_hamt:
    erts_factory_undo(factory);
    PSTACK_DESTROY(hamt_array);
    if (ctx) {
	ctx->state = B2TDecodeFail;
	ctx->reds = reds;
    }
    WSTACK_DESTROY(flat_maps);
        
    return NULL;
}

/* returns the number of bytes needed to encode an object
   to a sequence of bytes
   N.B. That this must agree with to_external2() above!!!
   (except for cached atoms) */
static Uint encode_size_struct2(ErtsAtomCacheMap *acmp, Eterm obj, unsigned dflags) {
    Uint res;
    (void) encode_size_struct_int(NULL, acmp, obj, dflags, NULL, &res);
    return res;
}

static int
encode_size_struct_int(TTBSizeContext* ctx, ErtsAtomCacheMap *acmp, Eterm obj,
		       unsigned dflags, Sint *reds, Uint *res)
{
    DECLARE_WSTACK(s);
    Uint m, i, arity;
    Uint result = 0;
    Sint r = 0;

    if (ctx) {
	WSTACK_CHANGE_ALLOCATOR(s, ERTS_ALC_T_SAVED_ESTACK);
	r = *reds;

	if (ctx->wstack.wstart) { /* restore saved stack */
	    WSTACK_RESTORE(s, &ctx->wstack);
	    result = ctx->result;
	    obj = ctx->obj;
	}
    }

#define LIST_TAIL_OP ((0 << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_HEADER)
#define TERM_ARRAY_OP(N) (((N) << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_HEADER)
#define TERM_ARRAY_OP_DEC(OP) ((OP) - (1 << _TAG_PRIMARY_SIZE))


    for (;;) {
	ASSERT(!is_header(obj));

	if (ctx && --r == 0) {
	    *reds = r;
	    ctx->obj = obj;
	    ctx->result = result;
	    WSTACK_SAVE(s, &ctx->wstack);
	    return -1;
	}
	switch (tag_val_def(obj)) {
	case NIL_DEF:
	    result++;
	    break;
	case ATOM_DEF:
	    if (dflags & DFLAG_INTERNAL_TAGS) {
		if (atom_val(obj) >= (1<<16)) {
		    result += 1 + 3;
		}
		else {
		    result += 1 + 2;
		}
	    }
	    else {
		Atom *a = atom_tab(atom_val(obj));
		int alen;
		if ((dflags & DFLAG_UTF8_ATOMS) || a->latin1_chars < 0) {
		    alen = a->len;
		    result += 1 + 1 + alen;
		    if (alen > 255) {
			result++; /* ATOM_UTF8_EXT (not small) */
		    }
		}
		else {
		    alen = a->latin1_chars;
		    result += 1 + 1 + alen;
		    if (alen > 255 || !(dflags & DFLAG_SMALL_ATOM_TAGS))
			result++; /* ATOM_EXT (not small) */
		}
		insert_acache_map(acmp, obj, dflags);
	    }
	    break;
	case SMALL_DEF:
	    {
		Sint val = signed_val(obj);

		if ((Uint)val < 256)
		    result += 1 + 1;		/* SMALL_INTEGER_EXT */
		else if (sizeof(Sint) == 4 || IS_SSMALL32(val))
		    result += 1 + 4;		/* INTEGER_EXT */
		else {
		    DeclareTmpHeapNoproc(tmp_big,2);
		    UseTmpHeapNoproc(2);
		    i = big_bytes(small_to_big(val, tmp_big));
		    result += 1 + 1 + 1 + i;	/* SMALL_BIG_EXT */
		    UnUseTmpHeapNoproc(2);
		}
	    }
	    break;
	case BIG_DEF:
	    i = big_bytes(obj);
	    if (sizeof(Sint)==4 && i <= 4 && (big_digit(obj,0)-big_sign(obj)) < (1<<31))
		result += 1 + 4;          /* INTEGER_EXT */
	    else if (i < 256)
		result += 1 + 1 + 1 + i;  /* tag,size,sign,digits */
	    else
		result += 1 + 4 + 1 + i;  /* tag,size,sign,digits */
	    break;
        case EXTERNAL_PID_DEF:
            if (external_pid_creation(obj) > ERTS_MAX_LOCAL_CREATION)
                result += 3;
            /*fall through*/
	case PID_DEF:
	    result += (1 + encode_size_struct2(acmp, pid_node_name(obj), dflags) +
		       4 + 4 + 1);
	    break;
        case EXTERNAL_REF_DEF:
            if (external_ref_creation(obj) > ERTS_MAX_LOCAL_CREATION)
                result += 3;
            /*fall through*/
	case REF_DEF:
	    ASSERT(dflags & DFLAG_EXTENDED_REFERENCES);
	    i = ref_no_numbers(obj);
	    result += (1 + 2 + encode_size_struct2(acmp, ref_node_name(obj), dflags) +
		       1 + 4*i);
	    break;
        case EXTERNAL_PORT_DEF:
            if (external_port_creation(obj) > ERTS_MAX_LOCAL_CREATION)
                result += 3;
            /*fall through*/
        case PORT_DEF:
	    result += (1 + encode_size_struct2(acmp, port_node_name(obj), dflags) +
		      4 + 1);
	    break;
	case LIST_DEF:
	    if ((m = is_string(obj)) && (m < MAX_STRING_LEN)) {
		result += m + 2 + 1;
	    } else {
		result += 5;
		WSTACK_PUSH2(s, (UWord)CDR(list_val(obj)), (UWord)LIST_TAIL_OP);
		obj = CAR(list_val(obj));
		continue; /* big loop */
	    }
	    break;
	case TUPLE_DEF:
	    {
		Eterm* ptr = tuple_val(obj);
		arity = arityval(*ptr);
		if (arity <= 0xff) {
		    result += 1 + 1;
		} else {
		    result += 1 + 4;
		}
		if (arity > 1) {
		    WSTACK_PUSH2(s, (UWord) (ptr + 2),
				    (UWord) TERM_ARRAY_OP(arity-1));
		}
                else if (arity == 0) {
		    break;
                }
		obj = ptr[1];
		continue; /* big loop */
	    }
	case MAP_DEF:
	    if (is_flatmap(obj)) {
		flatmap_t *mp = (flatmap_t*)flatmap_val(obj);
		Uint size = flatmap_get_size(mp);

		result += 1 + 4; /* tag + 4 bytes size */

                if (size) {
		    WSTACK_PUSH4(s, (UWord) flatmap_get_values(mp),
				    (UWord) TERM_ARRAY_OP(size),
		                    (UWord) flatmap_get_keys(mp),
				    (UWord) TERM_ARRAY_OP(size));
		}
	    } else {
		Eterm *ptr;
		Eterm hdr;
		Uint node_sz;
		ptr = boxed_val(obj);
		hdr = *ptr;
		ASSERT(is_header(hdr));
		switch(hdr & _HEADER_MAP_SUBTAG_MASK) {
		case HAMT_SUBTAG_HEAD_ARRAY:
		    ptr++;
		    node_sz = 16;
		    result += 1 + 4; /* tag + 4 bytes size */
		    break;
		case HAMT_SUBTAG_HEAD_BITMAP:
		    ptr++;
		    result += 1 + 4; /* tag + 4 bytes size */
		    /*fall through*/
		case HAMT_SUBTAG_NODE_BITMAP:
		    node_sz = hashmap_bitcount(MAP_HEADER_VAL(hdr));
		    ASSERT(node_sz < 17);
		    break;
		default:
		    erts_exit(ERTS_ERROR_EXIT, "bad header\r\n");
		}

		ptr++;
		WSTACK_RESERVE(s, node_sz*2);
		while(node_sz--) {
                    if (is_list(*ptr)) {
			WSTACK_FAST_PUSH(s, CAR(list_val(*ptr)));
			WSTACK_FAST_PUSH(s, CDR(list_val(*ptr)));
                    } else {
			WSTACK_FAST_PUSH(s, *ptr);
		    }
		    ptr++;
		}
	    }
	    break;
	case FLOAT_DEF:
	    if (dflags & DFLAG_NEW_FLOATS) {
		result += 9;
	    } else {
		result += 32;   /* Yes, including the tag */
	    }
	    break;
	case BINARY_DEF:
	    if (dflags & DFLAG_INTERNAL_TAGS) {
		ProcBin* pb = (ProcBin*) binary_val(obj);
		Uint sub_extra = 0;
		Uint tot_bytes = pb->size;
		if (pb->thing_word == HEADER_SUB_BIN) {
		    ErlSubBin* sub = (ErlSubBin*) pb;
		    pb = (ProcBin*) binary_val(sub->orig);
		    sub_extra = 2;  /* bitoffs and bitsize */
		    tot_bytes += (sub->bitoffs + sub->bitsize+ 7) / 8;
		}
		if (pb->thing_word == HEADER_PROC_BIN
		    && heap_bin_size(tot_bytes) > PROC_BIN_SIZE) {

		    result += 1 + sub_extra + sizeof(ProcBin);
		    break;
		}
	    }
	    result += 1 + 4 + binary_size(obj) +
		    5;			/* For unaligned binary */
	    break;
	case FUN_DEF:
	    {
		ErlFunThing* funp = (ErlFunThing *) fun_val(obj);
		
		if ((dflags & DFLAG_NEW_FUN_TAGS) != 0) {
		    result += 20+1+1+4;	/* New ID + Tag */
		    result += 4; /* Length field (number of free variables */
		    result += encode_size_struct2(acmp, funp->creator, dflags);
		    result += encode_size_struct2(acmp, funp->fe->module, dflags);
		    result += 2 * (1+4);	/* Index, Uniq */
		} else {
		    /*
		     * Size when fun is mapped to a tuple.
		     */
		    result += 1 + 1; /* Tuple tag, arity */
		    result += 1 + 1 + 2 +
			atom_tab(atom_val(am_fun))->len; /* 'fun' */
		    result += 1 + 1 + 2 +
			atom_tab(atom_val(funp->fe->module))->len; /* Module name */
		    result += 2 * (1 + 4); /* Index + Uniq */
		    result += 1 + (funp->num_free < 0x100 ? 1 : 4);
		}
		if (funp->num_free > 1) {
		    WSTACK_PUSH2(s, (UWord) (funp->env + 1),
				    (UWord) TERM_ARRAY_OP(funp->num_free-1));
		}
		if (funp->num_free != 0) {
		    obj = funp->env[0];
		    continue; /* big loop */
		}
		break;
	    }

	case EXPORT_DEF:
	    {
		Export* ep = *((Export **) (export_val(obj) + 1));
		result += 1;
		result += encode_size_struct2(acmp, ep->info.mfa.module, dflags);
		result += encode_size_struct2(acmp, ep->info.mfa.function, dflags);
		result += encode_size_struct2(acmp, make_small(ep->info.mfa.arity), dflags);
	    }
	    break;

	default:
	    erts_exit(ERTS_ERROR_EXIT,"Internal data structure error (in encode_size_struct2)%x\n",
		     obj);
	}

	if (WSTACK_ISEMPTY(s)) {
	    break;
	}
	obj = (Eterm) WSTACK_POP(s);

        if (is_header(obj)) {
            switch (obj) {
	    case LIST_TAIL_OP:
		obj = (Eterm) WSTACK_POP(s);
		if (is_list(obj)) {
		    Eterm* cons = list_val(obj);

		    WSTACK_PUSH2(s, (UWord)CDR(cons), (UWord)LIST_TAIL_OP);
		    obj = CAR(cons);
		}
		break;

	    case TERM_ARRAY_OP(1):
		obj = *(Eterm*)WSTACK_POP(s);
		break;
	    default: { /* TERM_ARRAY_OP(N) when N > 1 */
		Eterm* ptr = (Eterm*) WSTACK_POP(s);
		WSTACK_PUSH2(s, (UWord) (ptr+1),
			        (UWord) TERM_ARRAY_OP_DEC(obj));
		obj = *ptr;
	    }
	    }
	}
    }

    WSTACK_DESTROY(s);
    if (ctx) {
	ASSERT(ctx->wstack.wstart == NULL);
	*reds = r;
    }
    *res = result;
    return 0;
}



static Sint
decoded_size(byte *ep, byte* endp, int internal_tags, B2TContext* ctx)
{
    int heap_size;
    int terms;
    int atom_extra_skip;
    Uint n;
    SWord reds;

    if (ctx) {
        reds = ctx->reds;
        if (ctx->u.sc.ep) {
            heap_size = ctx->u.sc.heap_size;
            terms = ctx->u.sc.terms;
            ep = ctx->u.sc.ep;
            atom_extra_skip = ctx->u.sc.atom_extra_skip;
            goto init_done;
        }
    }
    else
        reds = 0; /* not used but compiler warns anyway */

    heap_size = 0;
    terms = 1;
    atom_extra_skip = 0;
init_done:

#define SKIP(sz)				\
    do {					\
	if ((sz) <= endp-ep) {			\
	    ep += (sz);				\
        } else { goto error; };			\
    } while (0)

#define SKIP2(sz1, sz2)				\
    do {					\
	Uint sz = (sz1) + (sz2);		\
	if (sz1 < sz && (sz) <= endp-ep) {	\
	    ep += (sz);				\
        } else { goto error; }			\
    } while (0)

#define CHKSIZE(sz)				\
    do {					\
	 if ((sz) > endp-ep) { goto error; }	\
    } while (0)

#define ADDTERMS(n)				\
    do {					\
        int before = terms;		        \
	terms += (n);                           \
	if (terms < before) goto error;     	\
    } while (0)

    ASSERT(terms > 0);
    do {
        int tag;
	CHKSIZE(1);
	tag = ep++[0];
	switch (tag) {
	case INTEGER_EXT:
	    SKIP(4);
#if !defined(ARCH_64)
	    heap_size += BIG_UINT_HEAP_SIZE;
#endif
	    break;
	case SMALL_INTEGER_EXT:
	    SKIP(1);
	    break;
	case SMALL_BIG_EXT:
	    CHKSIZE(1);
	    n = ep[0];		/* number of bytes */
	    SKIP2(n, 1+1);		/* skip size,sign,digits */
	    heap_size += 1+(n+sizeof(Eterm)-1)/sizeof(Eterm); /* XXX: 1 too much? */
	    break;
	case LARGE_BIG_EXT:
	    CHKSIZE(4);
	    n = get_int32(ep);
	    if (n > BIG_ARITY_MAX*sizeof(ErtsDigit)) {
		goto error;
	    }
	    SKIP2(n,4+1);		/* skip, size,sign,digits */
	    heap_size += 1+1+(n+sizeof(Eterm)-1)/sizeof(Eterm); /* XXX: 1 too much? */
	    break;
	case ATOM_EXT:
	    CHKSIZE(2);
	    n = get_int16(ep);
	    if (n > MAX_ATOM_CHARACTERS) {
		goto error;
	    }
	    SKIP(n+2+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;
	case ATOM_UTF8_EXT:
	    CHKSIZE(2);
	    n = get_int16(ep);
	    ep += 2;
	    if (n > MAX_ATOM_SZ_LIMIT) {
		goto error;
	    }
	    SKIP(n+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;
	case SMALL_ATOM_EXT:
	    CHKSIZE(1);
	    n = get_int8(ep);
	    if (n > MAX_ATOM_CHARACTERS) {
		goto error;
	    }
	    SKIP(n+1+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;
	case SMALL_ATOM_UTF8_EXT:
	    CHKSIZE(1);
	    n = get_int8(ep);
	    ep++;
	    if (n > MAX_ATOM_SZ_LIMIT) {
		goto error;
	    }
	    SKIP(n+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;
	case ATOM_CACHE_REF:
	    SKIP(1+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;
        case NEW_PID_EXT:
	    atom_extra_skip = 12;
	    goto case_PID;
        case PID_EXT:
	    atom_extra_skip = 9;
	case_PID:
	    /* In case it is an external pid */
	    heap_size += EXTERNAL_THING_HEAD_SIZE + 1;
	    terms++;
	    break;
        case NEW_PORT_EXT:
	    atom_extra_skip = 8;
	    goto case_PORT;
        case PORT_EXT:
	    atom_extra_skip = 5;
	case_PORT:
	    /* In case it is an external port */
	    heap_size += EXTERNAL_THING_HEAD_SIZE + 1;
	    terms++;
	    break;
	case NEWER_REFERENCE_EXT:
	    atom_extra_skip = 4;
	    goto case_NEW_REFERENCE;
        case NEW_REFERENCE_EXT:
	    atom_extra_skip = 1;
	case_NEW_REFERENCE:
	    {
		int id_words;

		CHKSIZE(2);
		id_words = get_int16(ep);
		    
		if (id_words > ERTS_MAX_REF_NUMBERS)
		    goto error;

		ep += 2;
		atom_extra_skip += 4*id_words;
		/* In case it is an external ref */
#if defined(ARCH_64)
		heap_size += EXTERNAL_THING_HEAD_SIZE + id_words/2 + 1;
#else
		heap_size += EXTERNAL_THING_HEAD_SIZE + id_words;
#endif
		terms++;
		break;
	    }
	case REFERENCE_EXT:
	    /* In case it is an external ref */
	    heap_size += EXTERNAL_THING_HEAD_SIZE + 1;
	    atom_extra_skip = 5;
	    terms++;
	    break;
	case NIL_EXT:
	    break;
	case LIST_EXT:
	    CHKSIZE(4);
	    n = get_int32(ep);
	    ep += 4;
	    ADDTERMS(n);
	    terms++;
	    heap_size += 2 * n;
	    break;
	case SMALL_TUPLE_EXT:
	    CHKSIZE(1);
	    n = *ep++;
	    terms += n;
	    heap_size += n + 1;
	    break;
	case LARGE_TUPLE_EXT:
	    CHKSIZE(4);
	    n = get_int32(ep);
	    ep += 4;
	    ADDTERMS(n);
	    heap_size += n + 1;
	    break;
	case MAP_EXT:
	    CHKSIZE(4);
	    n = get_int32(ep);
	    ep += 4;
	    ADDTERMS(2*n);
            if (n <= MAP_SMALL_MAP_LIMIT) {
                heap_size += 3 + n + 1 + n;
            } else {
                heap_size += HASHMAP_ESTIMATED_HEAP_SIZE(n);
            }
	    break;
	case STRING_EXT:
	    CHKSIZE(2);
	    n = get_int16(ep);
	    SKIP(n+2);
	    heap_size += 2 * n;
	    break;
	case FLOAT_EXT:
	    SKIP(31);
	    heap_size += FLOAT_SIZE_OBJECT;
	    break;
	case NEW_FLOAT_EXT:
	    SKIP(8);
	    heap_size += FLOAT_SIZE_OBJECT;
	    break;
	case BINARY_EXT:
	    CHKSIZE(4);
	    n = get_int32(ep);
	    SKIP2(n, 4);
	    if (n <= ERL_ONHEAP_BIN_LIMIT) {
		heap_size += heap_bin_size(n);
	    } else {
		heap_size += PROC_BIN_SIZE;
	    }
	    break;
	case BIT_BINARY_EXT:
	    {
		CHKSIZE(5);
		n = get_int32(ep);
		SKIP2(n, 5);
		if (n <= ERL_ONHEAP_BIN_LIMIT) {
		    heap_size += heap_bin_size(n) + ERL_SUB_BIN_SIZE;
		} else {
		    heap_size += PROC_BIN_SIZE + ERL_SUB_BIN_SIZE;
		}
	    }
	    break;
	case EXPORT_EXT:
	    terms += 3;
	    heap_size += 2;
	    break;
	case NEW_FUN_EXT:
	    {
		unsigned num_free;
		Uint total_size;

		CHKSIZE(1+16+4+4);
		total_size = get_int32(ep);
		CHKSIZE(total_size);		
		ep += 1+16+4+4;
		/*FALLTHROUGH*/

	    case FUN_EXT:
		CHKSIZE(4);
		num_free = get_int32(ep);
		ep += 4;
		if (num_free > MAX_ARG) {
		    goto error;
		}
		terms += 4 + num_free;
		heap_size += ERL_FUN_SIZE + num_free;
		break;
	    }
	case ATOM_INTERNAL_REF2:
	    SKIP(2+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;
	case ATOM_INTERNAL_REF3:
	    SKIP(3+atom_extra_skip);
	    atom_extra_skip = 0;
	    break;

	case BINARY_INTERNAL_REF:
	    if (!internal_tags) {
		goto error;
	    }
	    SKIP(sizeof(ProcBin));
	    heap_size += PROC_BIN_SIZE;
	    break;
	case BIT_BINARY_INTERNAL_REF:
	    if (!internal_tags) {
		goto error;
	    }
	    SKIP(2+sizeof(ProcBin));
	    heap_size += PROC_BIN_SIZE + ERL_SUB_BIN_SIZE;
	    break;
	default:
	    goto error;
	}
        terms--;

        if (ctx && --reds <= 0 && terms > 0) {
            ctx->u.sc.heap_size = heap_size;
            ctx->u.sc.terms = terms;
            ctx->u.sc.ep = ep;
            ctx->u.sc.atom_extra_skip = atom_extra_skip;
            ctx->reds = 0;
            return 0;
        }
    }while (terms > 0);

    /* 'terms' may be non-zero if it has wrapped around */
    if (terms == 0) {
        if (ctx) {
            ctx->state = B2TDecodeInit;
            ctx->reds = reds;
        }
        return heap_size;
    }

error:
    if (ctx) {
        ctx->state = B2TBadArg;
    }
    return -1;
#undef SKIP
#undef SKIP2
#undef CHKSIZE
}